Biodegradable magnesium-based alloy for medical applications

Abstract

The present invention relates to biodegradable magnesium-based alloys and methods for the manufacture of such alloys. Specifically, the biodegradable magnesium-based alloy may be an alloy comprising other elements such as zinc (Zn), calcium (Ca) and zirconium (Zr). More specifically, the biodegradable magnesium-based alloy is characterized by properties such as yield strength of at least 120 MPa and a degradation rate of less than 6 mm per year, which renders the alloy suitable for use in medical implants, such as for bone fixation.

Description

P6368PC00Biodegradable magnesium-based alloy for medical applicationsTechnical fieldThe present invention relates to biodegradable magnesium-based alloys and methods for the manufacture of such alloys. Specifically, the biodegradable magnesium-based alloy may be an alloy comprising other elements such as zinc (Zn), calcium (Ca) and zirconium (Zr). More specifically, the biodegradable magnesium-based alloy is characterized by properties such as yield strength of at least 120 MPa and a degradation rate of less than 6 mm per year, which renders the alloy suitable for use in medical implants, such as for bone fixation.BackgroundMagnesium (Mg) is both one of the lightest and most abundant metals available in the Earth crust, which makes it a very attractive element for engineering purposes. At the same time, pure Mg has rather high chemical reactivity, relatively low strength, and limited technological plasticity.Magnesium-based alloys have gained some attention in the field of biomedical implants due to their attainable ranges of mechanical properties and biodegradability. These alloys are particularly promising for use in temporary implants, such as bone fixation devices, where the gradual resorption of the material in the body eliminates the need for secondary surgeries to remove the implant. Existing magnesium alloys, such as those alloyed with zinc, calcium, and rare-earth elements, have demonstrated potential for these applications. However, challenges remain in achieving a balance between sufficient mechanical strength, a controlled degradation rate which aligns with the biological healing process, and good biocompatibility of alloying elements. In particular, the use of certain heavy-metal elements for alloying, such as rare-earth elements, introduces concerns regarding long-term biocompatibility and potential toxicity, as their effects on human health remain poorly understood.One of the most efficient alloy systems from sufficient performance and good biocompatibility perspectives is based on alloying Mg with zinc and calcium. In such systems, Zn is added for improving alloy strength through solid-solutioning and / or precipitation strengthening, while Ca is added for improving corrosion resistance.P6368PC00However, challenges remain in achieving a balance between sufficient mechanical strength and a controlled degradation rate, which aligns with the biological healing process. For instance, Mg alloy ZX50 having 5.0 wt.% Zn and 0.30 wt.% Ca (that are rather high considering respective solubility limits) demonstrates excellent strength but mediocre degradation resistance (Hofstetter etal (2014)), while alloy ZX00 with low quantities of 0.50 wt.% Zn and 0.15 wt.% Ca has opposite performance, i.e. good corrosion resistance but low strength (Holweg etal (2020)).Another significant issue with existing magnesium-based alloys is insufficient control over microstructure during manufacturing. The formation of undesirable precipitates, large grain sizes, or non-uniform phase distributions can compromise both the mechanical and degradation properties of the alloy. These microstructural inconsistencies are often a result of poorly defined processing parameters, which lead to variability in material performance. As a result, the reproducibility and reliability of current alloys for medical implants remain suboptimal, limiting their widespread adoption in clinical settings.It is therefore an objective of the present disclosure to provide a magnesium-based alloy composition and associated manufacturing methods that address the aforementioned limitations. The invention aims to achieve an optimal balance between mechanical strength and degradation rate, ensuring reliable structural support for bone fixation while maintaining controlled biodegradability. Furthermore, the present disclosure seeks to ensure the biocompatibility of the alloy by avoiding the use of rare-earth elements and other potentially toxic elements and / or materials, while introducing innovative approaches to microstructure control for enhanced performance and consistency.SummaryOne aspect of the present invention is directed to a MgZnCaZr quaternary biodegradable magnesium-based alloy comprising medium weight percentage of Zn, low weight percentages of Ca and Zr, and with Mg as the primary component constituting at least 90 % by weight of the alloy. The invention also encompasses compositions comprising this alloy, its use in the manufacture of medical implants, andP6368PC00also a method for the manufacture thereof, which includes specific thermo- and / or mechanical processing steps to achieve the desired alloy properties.The alloy described in the present disclosure and obtained via the described thermomechanical processing provides several advantages in the context of medical implants. The exemplified narrow elemental compositions ensure a balance between mechanical strength and a controlled degradation rate, making it suitable for temporary biomedical implant applications such as bone fixation. Furthermore, the alloy according to the present invention does not comprise and / or is essentially free of rare-earth elements and therefore presents a biocompatible solution, addressing concerns associated with long-term safety.Another aspect of the present invention is directed to a method for producing the alloy comprising at least a step of homogenizing the microstructure of the as-cast alloy and which method emphasizes control over microstructure through sequential heattreatment steps. This method reduces the amount of undesirable primary precipitates to a manageable level and promotes a homogeneous microstructure, which enhances the alloy's mechanical and corrosion properties through achieving the ‘super-saturated solid solution’ state. In such a state, the alloying elements provide sufficient mechanical (yield) strength while minimising degradation rate. It is emphasized that homogenizing the microstructure by carefully matching both selected alloy composition range and heat treatment steps allows for final (biodegradable) alloy materials that are provided with the balance between degradation rate levels conventionally only attained by minimising the amounts of selected alloying elements and strength levels conventionally only attained after deformation processing such as hot-extrusions. The processing method described herein thereby provides biodegradable alloys with extrusion-level strengths and homogenous corrosion properties while at the same time cutting out a process step, making the manufacture of such alloys both simpler and more cost effective.The biodegradable alloy encompassed within the scope of the present invention provides at least a yield strength and degradation rate that align with the needs in the field of biodegradable orthopaedic implants. Orthopaedic implants are well known in the field and are generally used to replace, support or repair damaged bones, joints or cartilage. References made herein to specific properties of the biodegradable alloyP6368PC00(strengths, degradation rates, etc.) should be understood as also including a reference to the same properties of a composition comprising the alloy, such as an orthopaedic implant comprising or consisting of the biodegradable alloy. Orthopaedic implants may include by way of non-limiting example, screws, plates, rods, wires, and nails. The composition and manufacturing method may also be implemented in other biodegradable medical applications, such as gastric stents, external fixation and auxiliary or prosthetic devices, or find use in non-medical fields where light-weight structural metal alloys are desirable such as in the aerospace and automotive industries.Description of DrawingsFigure 1 : SEM images of an exemplary alloy within the present disclosure. The SEM images illustrate: (a) as-cast; (b, c, d) same alloy at different magnifications after homogenization I solid-solution treatment; and (e, f) following extrusion following the approach laid out in the examples. White spots indicate incoherent precipitate particlesFigure 2: Schematics of (a) agglomerated primary precipitates located along grain boundaries and triple junctions (seen also in Fig 1a), and (b) secondary precipitate particles within a unit cell in Mg alloys, along with examples of secondary precipitate particles as found in real-life alloys obtained in TEM micrographs showing (c) prismatic platelets, (d) basal platelets, and (e) <c>-axis rods, reproduced from J.-F. Nie (2012).Figure 3: TEM micrograph of a magnesium-based alloy according to the present disclosure. The TEM images were taken in high-angle annual diffraction (HAADF) mode on samples subjected to solid-solution heat treatment (homogenization) and natural aging (NA) at ambient temperature for a year (a,b), or homogenization and artificial peak aging (PA) at 150°C (c,d) or 180°C (e,f). Respective selected area electron diffraction (SAED) patterns shown in inserts, i.e.,

[0002] for the left and

[1120] for the right column. White-contrast features (small near-round and elongated) indicate secondary precipitate particles, (g) shows bright-field TEM micrograph of a sample after homogenization and extrusion with secondary precipitate particles seen as small near-round black features.P6368PC00Figure 4: Representative examples of the dependence of time on Vickers hardness values in (A) homogenised and (B) homogenised-and-extruded medium-Zn alloys during aging at 150 °C. The figure illustrates that while extruded samples have an initially higher Vickers hardness, the aging at 150 °C does not provide significant further improvement of this property. The reverse is seen for the homogenized (solidsolution treated) samples, initially having a lower Vickers hardness of approximately 55 HV, which over 40 hours increases to over 70 HV with aging at 150 °C. Importantly, this illustrates that extrusion-level strengths can be provided even without the need for extrusion processing.Figure 5: Macroscopic images of three different magnesium-based alloy samples according to the present disclosure after degradation testing in HBSS at 37°C for 7 days. The samples denoted as ‘Homogenized’ were prepared according to the process outlined in Example 1 herein. The samples denoted as ‘Extruded’ were prepared according to the process outlined in Example 2 herein. The samples denoted as ‘PA180°C’ were prepared according to the process outlined in Example 3 herein. The samples denoted as ‘PA150°C’ were prepared according to the process outlined in Example 3 herein with artificial ageing carried out at 150°C for 28-43 hours. The samples are furthermore classified as ‘high’, ‘medium’, or ‘low’ according to their relative content of zinc, being 4.1 wt.%, 3.7 wt.%, or 3.1 wt.%, respectively (see also the Examples section herein).Figure 6: Schematic representation of one or more embodied process flow maps for the fabrication of magnesium-based alloys according to the present disclosure and exemplified below in the examples. From left to right, the columns (or process flows) may be referred to as first column, second column, third column, and fourth column.Detailed descriptionThe present invention is directed to the field of biodegradable magnesium-based alloys comprising medium weight percentage of Zn, low weight percentages of Ca and Zr, and with Mg as the primary component, i.e. Mg constituting at least 90 % by weight of the alloy. Conventional terminology within the field commonly designates the primary alloying constituent as the ‘base element’ or ‘balance element’. In the present application, this may be expressed as ‘Mg (base)’ or ‘Mg (balance)’, which terms areP6368PC00used interchangeably. In all cases, they are to be interpreted as indicating that magnesium constitutes the remainder of the alloy composition up to 100 wt.%. Further in one or more embodiments as described herein, magnesium as the balance element may also be explicitly referred to as “wherein the remainder of the alloy is magnesium”.Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in art to which the subject matter herein belongs. As used herein, the following definitions are supplied to facilitate the understanding of the present invention.The term “comprise” is generally used in the sense of include, that is to say permitting the presence of one or more features or components. In addition, as used in the description and claims, the language "comprising" can also include analogous embodiments described in terms of “consisting of” and / or “consisting essentially of”.As used in the description and claims, the term "and / or" used in a phrase such as "A and / or B" herein is intended to include "A and B", "A or B", "A", and "B".As used in the description and claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. Similarly, terms such as “one or more” or “at least one” include both the singular and plural form of the respective feature.In one or more embodiments, the present disclosure relates to a biodegradable alloy and a manufacturing method thereof. The biodegradable alloy according to the present disclosure may also herein be referred to simply as “the alloy” and should be construed as referring to biodegradable alloy obtained according to the processes described within the scope of the disclosure. Accordingly, the as-cast alloys described herein (i.e. without any homogenization or other processing steps other than melting and solidification) are not encompassed when referring to “the alloy” of the present disclosure, unless explicitly stated otherwise.In one or more embodiments of the present disclosure, the biodegradable alloy is a magnesium-based alloy, and is more preferably a biodegradable alloy of magnesium comprising at least two auxiliary alloying elements, even more preferably three or moreP6368PC00auxiliary alloying elements. In one or more embodiments of the present disclosure, the biodegradable alloy of magnesium comprises at least two auxiliary alloying elements. In one or more embodiments of the present disclosure, the biodegradable alloy described herein is a ternary metal alloy, or a quaternary metal alloy. As used herein, the term “biodegradable alloy” should be construed as referring to a metal alloy which undergoes a degradation process, such as in one example by corrosion, under physiological conditions such as ion balance and pH. The rate at which the biodegradable alloy degrades and / or disintegrates under physiological conditions should preferably be in the range of 0.5 mm / year to 10 mm / year, more preferably in the range of 0.5 mm / year to 6 mm / year, to be suitable for, among other things, orthopaedic implants. As used herein, such degradation rate, expressed as a thickness loss in mm / year, primarily reflects material loss caused by corrosion processes. For the purposes of the present application, the degradation rate may therefore also be referred to as a corrosion rate, and the terms degradation rate and corrosion rate are used interchangeably.In one or more embodiments of the present disclosure, the biodegradable alloy comprises in addition to magnesium (Mg) as the base element also a specified percentage by weight of a plurality, such as at least 2, of the elements zinc (Zn), calcium (Ca), and zirconium (Zr). The term ‘percent by weight’ or ‘weight percent’ may within the present disclosure also be referred to as wt.% or %m (mass %). The careful selection and interplay between magnesium, calcium and zinc governs the balance between mechanical strength and degradation rate of the final alloy.In one or more embodiments of the present disclosure, the alloy is characterized by a zinc (Zn) content ranging from 2.0 to 6.0 wt.% based on weight of the alloy. In one or more embodiments, the zinc content of the alloy may be from 2.0 to 3.0 wt.%, from 3.0 to 4.0 wt.%, from 4.0 to 5.0 wt.%, or from 5.0 to 6.0 wt.%. In one or more embodiments, the zinc content of the alloy may be from 2.5 to 4.5 wt.%, such as from 2.6 to 4.4 wt.%, such as from 2.7 to 4.3 wt.%, such as from 2.8 to 4.2 wt.%, such as from 2.9 to 4.1 wt.%, such as from 3.0 to 4.0 wt.%, such as from 3.1 to 3.9 wt.%, such as from 3.2 to 3.8 wt.%, such as from 3.3 to 3.7 wt.%, such as from 3.4 to 3.6 wt.%. In one or more embodiments, the zinc content may be 2.5 wt.%, 2.6 wt.%, 2.7 wt.%, 2.8 wt.%, 2.9 wt.%, 3.0 wt.%, 3.1 wt.%, 3.2 wt.%, 3.3 wt.%, 3.4 wt.%, 3.5 wt.%, 3.6 wt.%, 3.7 wt.%, 3.8 wt.%, 3.9 wt.%, 4.0 wt.%, 4.1 wt.%, 4.2 wt.%, 4.3 wt.%, 4.4 wt.%, or 4.5 wt.%. InP6368PC00one or more embodiments, the zinc content of the alloy is preferably from 3.0 (± 0.2) wt.% to 4.0 (± 0.2) wt.%, such as from 3.0 (± 0.1) wt.% to 4.0 (± 0.1) wt.%, such as from 3.0 to 4.0 wt.%. In one or more embodiments, the zinc content of the alloy is preferably 3.7 (±1.0) wt.%, such as 3.7 (±0.5) wt.%, such as 3.7 (±0.2) wt.%, such as 3.7 (±0.1) wt.%.Within the alloy, the amount of Zn contributes to the solid-solution and precipitation strengthening of the alloy, which impacts the final mechanical performance of the biodegradable alloy. As such, it is contemplated that the function of zinc is to strengthen the material through solid-solution and / or the formation of secondary precipitates. In the alloys described herein which are heat-treated for the purpose of forming solid-solution (also referred to as homogenization), Zn atoms provide barriers for the movement of dislocations and thereby leads to material strengthening. In the alloys described herein which are heat-treated for the purpose of aging, Mg-Zn binary and Mg-Zn based ternary precipitate particles also act as very efficient barriers for movement of dislocations thus contributing even more to the material strengthening during and / or after the aging step(s). The efficiency of such strengthening increases however only to the extent that the Mg-Zn particles remain in coherency or in semicoherency with the Mg matrix. If, during aging, the Mg-Zn particles become so large that coherency is lost (i.e. they become incoherently bound to the matrix) this in-turn leads to a decrease of strengthening efficiency and increase of alloy degradation rate. Without wishing to be bound by any particular theory, it is speculated that the observed increased degradation rate in such systems comprising incoherently bound precipitate particles may be due to galvanic coupling at the interface of the matrix and large precipitate particles.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of 3d transition metals other than Zn. As used herein, a ‘3d transition metal’ has the same meaning as used in the technical field of metal alloys, and refers to elements and / or metals having atomic number 21 (Sc) to 30 (Zn). In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of one or more of manganese, chromium, vanadium, iron, nickel, copper and cobalt, such as is characterized by not comprising one or more of manganese, chromium, vanadium, iron, nickel, copper and cobalt.P6368PC00In one or more embodiments of the present disclosure, the alloy is characterized by a calcium (Ca) content ranging from 0.05 wt.% to 0.30 wt.%. based on weight of the alloy, such as 0.05 wt.% to 0.20 wt.%, such as 0.10 wt.% to 0.15 wt.%. In one or more embodiments of the present disclosure, the calcium content is 0.15 (± 0.5) wt.%, such as 0.15 (± 0.4) wt.%, such as 0.15 (± 0.3) wt.%, such as 0.15 (± 0.2) wt.%, such as 0.15 (± 0.1 ) wt.%, such as 0.15 wt.%. In one or more embodiments, the calcium content may be 0.10 wt.%, 0.11 wt.%, 0.12 wt.%, 0.13 wt.%, 0.14 wt.%, or 0.15 wt.%.Calcium enhances corrosion resistance and / or reduces degradation rates in addition to also contributing to solid-solution and precipitate strengthening. Precipitate strengthening (i.e. formation of precipitates) may increase the degradation rate of the alloy if not controlled and the presence of precipitates is therefore desirable to minimize during alloy solidification and thermo-mechanical processing.The precise control of calcium levels in the alloys described herein will therefore play a role in controlling the formation of in particular ternary alloy primary precipitates that could compromise mechanical properties and / or accelerate degradation. In one or more embodiments, the specified calcium content reduces the formation of such ternary alloy precipitates in the biodegradable alloy, thereby improving relevant properties for biomedical applications.The present inventors have identified a narrow elemental composition range, which is demonstrated to provide superior properties by balancing the relative amounts of in particular zinc and calcium so as to provide sufficient strength for biomechanical purposes while avoiding excessive formation of ternary intermetallic precipitates that could accelerate corrosion.In one or more embodiments of the present disclosure, the zirconium (Zr) content ranges from 0.001 wt.% to 0.30 wt.%, such as from 0.01 wt. % to 0.30 wt. %, such as from 0.10 wt.% to 0.30 wt.%. In one or more embodiments, the zirconium content is from 0.001 wt.% to 0.05 wt.%, such as from 0.05 wt.% to 0.10 wt.%, such as from 0.10 wt.% to 0.15 wt.%, such as from 0.15 wt.% to 0.20 wt.%, such as from 0.20 wt.% to 0.25 wt.%, such as from 0.25 wt.% to 0.30 wt.%. In one or more embodiments of the present disclosure, the zirconium content is from 0.05 wt.% to 0.35 wt.%. In one or more embodiments of the present disclosure, the zirconium content is 0.15 (± 0.5)P6368PC00wt.%, such as 0.15 (± 0.4) wt.%, such as 0.15 (± 0.3) wt.%, such as 0.15 (± 0.2) wt.%, such as 0.15 (± 0.1) wt.%, such as 0.15 wt.%.Zirconium is employed within the biodegradable alloy of the present disclosure for the dual purpose of i) refinement of the microstructure grain size during material solidification, and ii) to encapsulate any potential iron impurities, to the extent that such may be present from the casting process. Zirconium is known as one of the most powerful grain refiners of magnesium alloys where it can aid in providing both fine grain sizes as well as uniformities in microstructure and mechanical properties. According to well-established Hall-Petch relationship, the strength of a metal (or alloy) increases as the grain size approaches the nano-size regime. The observed effect arises from the high proportion of grain boundaries at which dislocations may become immobilized. The small grain size and uniform microstructure obtained by the action of zirconium provides, for the specific narrow elemental compositions of the present disclosure, superior properties in the form of both mechanical strength and corrosion resistance. In one or more embodiments of the present disclosure, the mentioned improved properties may be provided even in the absence of a structural and / or plastic deformation step such as extrusion. Furthermore, zirconium is known for its ability to encapsulate potential iron impurities due to solidification through peritectic reaction. Such impurities may be present in the metals used for the initial melt / casting, or may potentially be obtained from the surface of steel crucibles during melting (known as ‘iron pickup’). By the addition of zirconium to the alloy composition it is possible to mitigate the negative effects of such iron impurities on corrosion behavior of the final biodegradable alloy.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of rare-earth elements also sometimes referred to as rare-earth metals, f-elements and / or lanthanides / actinides. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of rare-earth elements, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% of rare-earth elements. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any rare-earth elements.P6368PC00In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of manganese. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of manganese, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% of manganese. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any manganese.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of chromium. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of chromium, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% of chromium. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any chromium.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of vanadium. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of vanadium, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% of vanadium. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any vanadium.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of iron. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of iron, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% ofP6368PC00iron. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any iron.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of nickel. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of nickel, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% of nickel. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any nickel.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of copper. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of copper, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% of copper. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any copper.In one or more embodiments of the present disclosure, the alloy is characterized by being essentially free of cobalt. That is to say, the alloy according to the present disclosure does in one or more embodiments comprise less than 1.0 wt.% of cobalt, such as less than 0.50 wt.%, such as less than 0.25 wt.%, such as less than 0.10 wt.%, such as less than 0.05 wt.%, such as less than 0.04 wt.%, such as less than 0.03 wt.%, such as less than 0.02 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.% of cobalt. In one or more embodiments of the present disclosure, the alloy is characterized by not comprising and / or containing any cobalt.In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.2) wt.% to 4.0 (± 0.2) wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.30 (± 0.05) wt.% of Ca;c. 0.001 wt.% to 0.30 wt.% of Zr;P6368PC00d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.2) wt.% to 4.0 (± 0.2) wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.30 (± 0.05) wt.% of Ca;c. 0.01 wt.% to 0.30 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.2) wt.% to 4.0 (± 0.2) wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.15 (± 0.05) wt.% of Ca;c. 0.10 (± 0.05) wt.% to 0.30 (± 0.05) wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.2) wt.% to 4.0 (± 0.2) wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.15 (± 0.05) wt.% of Ca;c. 0.10 (± 0.05) wt.% to 0.30 (± 0.05) wt.% of Zr; andd. optionally less than 0.05 wt.% of each of any unspecified element;wherein the remainder of the alloy is magnesium.In one or more embodiments of the present disclosure, the alloy is characterized by a composition consisting of:a. 3.0 (± 0.2) wt.% to 4.0 (± 0.2) wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.15 (± 0.05) wt.% of Ca;c. 0.10 (± 0.05) wt.% to 0.30 (± 0.05) wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (balance).P6368PC00In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.1) wt.% to 4.0 (± 0.1) wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.30 (± 0.05) wt.% of Ca;c. 0.001 wt.% to 0.30 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.1) wt.% to 4.0 (± 0.1) wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.30 (± 0.05) wt.% of Ca;c. 0.01 wt.% to 0.30 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.1) wt.% to 4.0 (± 0.1) wt.% of Zn;b. 0.15 (± 0.02) wt.% of Ca;c. 0.15 (± 0.02) wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 (± 0.1) wt.% to 4.0 (± 0.1) wt.% of Zn;b. 0.15 (± 0.05) wt.% of Ca;c. 0.10 (± 0.05) wt.% to 0.15 (± 0.05) of Zr; andd. optionally less than 0.05 wt.% of each of any unspecified element; wherein the remainder of the alloy is magnesium.In one or more embodiments of the present disclosure, the alloy is characterized by a composition consisting of:a. 3.0 (± 0.1) wt.% to 4.0 (± 0.1) wt.% of Zn;P6368PC00b. 0.15 (± 0.02) wt.% of Ca;c. 0.15 (± 0.02) wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (balance).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 wt.% to 4.0 wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.15 (± 0.05) wt.% of Ca;c. 0.001 wt.% to 0.30 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 wt.% to 4.0 wt.% of Zn;b. 0.10 (± 0.05) wt.% to 0.15 (± 0.05) wt.% of Ca;c. 0.01 wt.% to 0.30 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.0 wt.% to 4.0 wt.% of Zn;b. 0.10 wt.% to 0.15 wt.% of Ca;c. 0.10 wt.% to 0.20 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; and e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a composition comprising or consisting essentially of:a. 3.1 wt.% of Zn;b. 0.15 wt.% of Ca;c. 0.15 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; andP6368PC00e. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a chemical composition comprising or consisting essentially of:a. 3.7 wt.% of Zn;b. 0.15 wt.% of Ca;c. 0.15 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; ande. Mg (base).In one or more embodiments of the present disclosure, the alloy is characterized by a chemical composition comprising or consisting essentially of:a. 4.1 wt.% of Zn;b. 0.15 wt.% of Ca;c. 0.15 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element; ande. Mg (base).As used herein, the term ‘consisting essentially of’ permits the presence of additional components or, when referring to methods, additional steps, provided that any such components or steps do not materially affect the basic and novel characteristics of the claimed invention. This terminology allows for the presence of unavoidable impurities, trace constituents, or non-critical additives that do not alter the primary function or properties of the invention, as well as conventional or ancillary processing steps that do not materially influence the performance or character of the disclosed methods.By extension, the term ‘essentially free of’ is to be understood as indicating that the composition may contain a permitted amount of the specified element, provided that the amount present does not impart, modify, or otherwise deteriorate the relevant properties of the disclosed alloy composition. Within the meaning of the present disclosure, a composition will generally be regarded as ‘essentially free of’ the element when the element is present in an amount below about 1.0 wt.%, and preferably in an amount below about 0.020 wt.%, while also encompassing embodiments in which the element is entirely absent.P6368PC00As used herein, the term “unspecified element” refers to an element of the periodic table that may be present within the disclosed composition at levels so low that they do not constitute any intentional addition for the purpose of alloying. Within the meaning of the present disclosure, an alloying element is generally considered to be present in an amount of at least 0.05 wt.%. Conversely, an “unspecified element” is generally considered as present in an amount below this threshold, such as less than 0.05 wt.%, preferably less than 0.025 wt.%, more preferable less than 0.01 wt.%, even more preferable less than 0.005 wt.%. The term encompasses one or a multiple of such elements, provided that each individual element remains below the stated threshold. “Unspecified elements” may arise from residual impurities, unavoidable manufacturing artefacts, or trace contaminants that do not materially affect the basic and novel characteristics of the claimed alloy composition.In one or more embodiments of the present disclosure, the alloy has allowable impurities, such as from other unspecified elements, where the level of impurities is less than 0.05 wt.%, such as less than 0.02 wt.%, such as less than 0.015 wt.%, such as less than 0.01 wt.%, such as less than 0.005 wt.%.In one or more embodiments of the present disclosure, the alloy exhibits a structural degradation rate and / or corrosion rate of 10 mm per year (denoted mm / year) or lower. In one or more embodiments of the present disclosure, the structural degradation rate is 10 mm / year or lower, such as 9 mm / year or lower, such as 8 mm / year or lower, such as 7 mm / year or lower, such as 6 mm / year or lower, such as 5 mm / year or lower, such as 4 mm / year or lower, such as 3 mm / year or lower, such as 2 mm / year or lower, such as 1 mm / year or lower, preferably wherein the degradation rate and / or corrosion rate is studied and / or evaluated based on immersion tests in simulated body fluid, such as Hanks Balanced Salt Solution (HBSS). Evaluation of corrosion rate may also in one embodiment be evaluated according to standards ASTM G1 and / or G31 , such as ASTM G1-03 and / or G1-25 and / or G31-21 and / or G31-12.The corrosion of the alloy may be evaluated by an immersion corrosion test in accordance with ASTM G31 , such as ASTM G31 -12 or a later version such as G31 -21 , comprising updated terminology and details on test conditions. Based on the specified standard, test specimens may be immersed in a selected aqueous test medium for a predetermined exposure period under controlled conditions. After completion of theP6368PC00exposure, corrosion products may be removed from the specimen’s surface in accordance with ASTM G1 , such as ASTM G1-03, using a cleaning procedure selected to remove corrosion products while minimizing removal of the underlying base metal. The cleaning procedure may comprise chemical and / or mechanical cleaning and may be repeated until a substantially constant specimen mass is obtained. The mass loss of each specimen may then be determined. The corrosion rate may thereafter be calculated from the measured mass loss, the exposed surface area, the exposure time, and the material density, in accordance with the calculation method specified in ASTM G31.In a further embodiment, the degradation rate of the alloy, in particular when intended for use as a bioabsorbable medical implant, may be evaluated in accordance with ASTM F3268-18. According to the standard, the testing is conducted under physiologically relevant in vitro conditions, including immersion of test specimens in a simulated body fluid at a temperature of approximately 37 °C and a defined surface-area-to-solution-volume ratio. After a predetermined exposure period, corrosion products may be removed in accordance with specimen cleaning procedures such as those described in ASTM G1 , such as ASTM G1-03, and mass loss may then be determined. Degradation rates may be calculated from the measured mass loss, the exposed surface area, the exposure time, and the material density, consistent with immersion corrosion testing principles as defined in ASTM G31, such as ASTM G31-21.In one or more embodiments of the present disclosure, the alloy exhibits a structural degradation rate and / or corrosion rate below 1.0 mm / year, such as between 0.90 mm / year or lower, such as 0.80 mm / year or lower, such as 0.70 mm / year or lower, such as 0.60 mm / year or lower, preferably wherein the degradation rate and / or corrosion rate is studied and / or evaluated based on immersion tests in simulated body fluid, such as Hanks Balanced Salt Solution (HBSS).In one or more embodiments of the present disclosure, the alloy exhibits a structural degradation rate and / or corrosion rate of 0.5 to 2.0 mm / year, such as 0.5 to 1.5 mm / year, preferably wherein the degradation rate and / or corrosion rate is studied and / or evaluated based on immersion tests in simulated body fluid, such as Hanks Balanced Salt Solution (HBSS).P6368PC00The term ‘HBSS’ refers to a well-known salt-solution (pH = 7.4) corresponding to the blood plasma ionic composition, and comprising biocompatible cations such as sodium, calcium, magnesium and potassium, in combination with biocompatible anions such as chloride, bicarbonate, sulfate and phosphate. It is however not a limitation of the present disclosure that the evaluation is made in HBSS, and other (optionally buffered) salt solutions may be used for the evaluation of degradation rate and / or corrosion rate.In one or more embodiments of the present disclosure, the alloy exhibits a structural degradation rate and / or corrosion rate below 6 mm / year, such as from 0.3 mm / year to 6 mm / year. This rate allows sufficient structural integrity for orthopaedic implants during the healing process, while ensuring that the material biodegrades within a clinically relevant timeframe.In one or more embodiments of the present disclosure, the alloy is characterized by a tensile yield strength (TYS) ranging from 100 MPa to 350 MPa, such as 100 MPa to 110 MPa, such as 110 MPa to 120 MPa, such as 120 MPa to 130 MPa, such as 130 MPa to 140 MPa, such as 140 MPa to 150 MPa, such as 150 MPa to 160 MPa, such as 160 MPa to 170 MPa, such as 170 MPa to 180 MPa, such as 180 MPa to 200 MPa, such as 200 MPa to 220 MPa, such as 220 MPa to 240 MPa, such as 240 MPa to 260 MPa, such as 260 MPa to 300 MPa, such as 300 MPa to 350 MPa. The tensile yield strength may be estimated based on calculation from hardness measurements or more directly measured based on testing following ASTM E8 / E8M-22.In one or more embodiments of the present disclosure, the alloy is characterized by a tensile yield strength (TYS) ranging from 120 MPa to 170 MPa, such as a tensile yield strength (TYS) of 150 (±10) MPa.In one or more embodiments of the present disclosure, the alloy is characterized by an tensile yield strength (TYS) of 100 MPa or more, such as 110 MPa or more, such as 120 MPa or more, such as 130 MPa or more, such as 140 MPa or more, such as 150 MPa or more, such as 160 MPa or more, such as 170 MPa or more, such as 180 MPa or more, such as 190 MPa or more, such as 200 MPa or more, such as 220 MPa or more, such as 250 MPa or more.P6368PC00In one or more embodiments of the present disclosure, the alloy is characterized by an ultimate tensile strength (UTS) ranging from 100 MPa to 550 MPa, such as 100 MPa to 110 MPa, such as 110 MPa to 120 MPa, such as 120 MPa to 130 MPa, such as 130 MPa to 140 MPa, such as 140 MPa to 150 MPa, such as 150 MPa to 160 MPa, such as 160 MPa to 170 MPa, such as 170 MPa to 180 MPa, such as 180 MPa to 200 MPa, such as 200 MPa to 250 MPa, such as 250 MPa to 300 MPa, such as 300 MPa to 350 MPa, such as 350 MPa to 400 MPa, such as 400 MPa to 450 MPa, such as 450 MPa to 500 MPa.In one or more embodiments of the present disclosure, the alloy is characterized by an ultimate tensile strength (UTS) ranging from 120 MPa to 170 MPa, such as an ultimate tensile strength (UTS) of 150 (±10) MPa.In one or more embodiments of the present disclosure, the alloy is characterized by an ultimate tensile strength (UTS) of 100 MPa or more, such as 120 MPa or more, such as 140 MPa or more, such as 160 MPa or more, such as 180 MPa or more, such as 200 MPa or more, such as 220 MPa or more, such as 240 MPa or more, such as 260 MPa or more, such as 280 MPa or more, such as 300 MPa or more, such as 350 MPa or more, such as 400 MPa or more.When the alloy is characterized by the tensile strengths described herein, such as in particular ranging from 120 MPa to 170 MPa, this strength range is suitable for providing compatibility with the mechanical requirements of load-bearing orthopaedic implants, such as bone-screws or plates.In one or more embodiments of the present disclosure, the alloy is characterized by a Vickers hardness (HV) of at least 50. In one or more embodiments, the alloy may be characterized by a HV of at least 50 or more, such as 55 or more, such as 60 or more, such as 65 or more, such as 70 or more, such as 75 or more. In another embodiment, the alloy may be characterized by a HV from 40 to 130, such as from 50 to 60, such as from 60 to 70, such as from 70 to 80, such as from 55 to 65, such as from 65 to 75, such as 80 to 90, such as 90 to 100, such as 100 to 110, such as 110 to 120, such as 120 to 130.P6368PC00It is well within the capabilities of the skilled person to measure, or determine, one or more of Vickers hardness (HV), ultimate tensile strength (UTS), and tensile yield strength (TYS). Exemplary, Vickers hardness may be converted into tensile yield strengths in accordance with Pintaude (2022) or ISO 18265, such as ISO 18265:2013. Vickers Hardness (HV) may in one embodiment be evaluated according to ASTM E92, such as ASTM E92-23.In one embodiment, the hardness of the alloy is determined in accordance with ASTM E92-23 using the Vickers hardness test method. A diamond pyramid indenter may be applied to a surface of the alloy under a defined test force, such as 0.1 kgf, for a predetermined dwell time selected in accordance with ASTM E92-23, such as 10 s or 15 s. The dimensions of the resulting indentation may be measured and the Vickers hardness value may be calculated in accordance with ASTM E92-23.In one or more embodiments of the present disclosure, the alloy is characterized by a microstructure, such as a homogenous microstructure, comprising matrix grains having an effective average diameter of up to 200 pm, such as from 0.2 pm to 2 pm, such as from 2 pm to 4 pm, such as from 4 pm to 6 pm, such as from 6 pm to 8 pm, such as from 8 pm to 10 pm, such as from 10 pm to 15 pm, such as from 15 pm to 30 pm, such as from 30 pm to 50 pm, such as from 50 pm to 75 pm, such as from 75 pm to 200 pm.In one or more embodiments of the present disclosure, the alloy is characterized by a microstructure, such as a homogenous microstructure, comprising matrix grains having an effective average diameter of 1000 pm or less, such as 900 pm or less, such as 800 pm or less, such as 700 pm or less, such as 600 pm or less, such as 500 pm or less, such as 400 pm or less, such as 300 pm or less, such as 200 pm or less.In one or more embodiments of the present disclosure, the alloy is characterized by a microstructure average grain size of up to 15 pm, such as between 0.1 pm and 5 pm, 5 pm and 10 pm, and 10 pm to 15 pm.In one or more embodiments of the present disclosure, the alloy is characterized by a microstructure average grain size between 30 pm and 100 pm, such as between 45 pm and 75 pm, such as between 55 pm and 65 pm.P6368PC00In one or more embodiments of the present disclosure, the alloy comprises secondary precipitates such as prismatic platelets with a size ranging from 10 nm to 30 nm in diameter. These precipitates contribute to precipitation hardening, enhancing the alloy’s strength. Thicknesses of the prismatic platelet layers may range from two atomic layers to 2 nm or more, depending on the thermal and / or mechanical processing applied.As used herein, the term “matrix” is to be construed as referring to the dominant phase (also referred as alpha-phase) in the alloy microstructure consisting essentially of pure magnesium or solid solution of magnesium with alloying elements. By contrast, the term “precipitates” as used herein is to be construed as referring to all solid phases other than the matrix (including solid solution alpha-phase matrix) in the alloy microstructure. Such “precipitates” are further subdivided into “primary” and “secondary” precipitates herein (Fig. 2 is provided for a schematic illustration).The phrase “primary precipitates” as used herein, is to be construed as referring to precipitates that form during initial cooling of a melt to a solid alloy. At cooling rates typically used in industrial fabrication, they agglomerate in relatively large particle clusters that locate in the triple junctions of matrix grains and along grain boundaries, as illustrated in Fig. 2a. Within the meaning of the present disclosure, primary precipitates may in one example be binary or ternary alloys comprising at least two or more or Mg, Zn, Ca, and Zr. Ternary metal precipitates may generically be referred to herein simply as ternary MgZnCa particles. This nomenclature should not be interpreted as only referring to a 1 :1 :1 stoichiometric composition of Mg, Zn, and Ca, but instead refers to a composition of MgxZnyCaz, wherein x, y, and z may individually be selected as a non-negative integer, such as a value between 1 and 60. For brevity however, the shorthand notation ‘MgZnCa’ is used but may be used interchangeably with MgxZnyCaz. One example of a ternary MgZnCa precipitate is Mg6Zn3Ca2. The same nomenclature applies to binary MgZn and MgCa particles. Examples hereof include Mg2Ca and Mg4Zn7.The phrase “secondary precipitates” as used herein, is to be construed as referring to precipitates that form in post-cooling steps (also sometimes referred to herein as postsolidification), i.e. that form subsequent to formation of primary precipitates. Secondary precipitates may form during thermal and / or mechanical manipulation (one exampleP6368PC00being hot extrusion) of the solid alloy. As such, microstructure refinement and / or grain refinement such as during plastic deformation or heat treatments at elevated temperature may result in breaking-up or dissolution (i.e. refinement) of primary precipitates and / or the formation of secondary precipitates within the meaning of the present invention because these processes modulate the growth of secondary precipitates in the biodegradable alloy. The secondary precipitates grow in specific morphologies along specific crystallographic directions within the matrix grains as illustrated in Fig. 2b-e, which is in contrast to the primary precipitates that form along grain boundaries.Secondary precipitates having the same meaning as within the present disclosure are known from other magnesium-based alloying systems, and may be further subdivided into three types of secondary precipitates. These include “prismatic platelets”, “basal platelets”, and “<c>-axis rods” each name being indicative of which crystallographic directions the respective precipitate is found along in the magnesium hexagonal crystal lattice. Prismatic platelets as referred to herein are typical for Mg alloy systems containing rare-earth elements; basal platelets are typical for Mg alloy systems with aluminium as the principal alloying element; and <c>-axis rods are typical for Mg alloy systems with zinc as the principal alloying element.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by comprising less than 10 wt.% of primary precipitates, such as less than 5.0 wt.%, such as less than 4.0 wt.%, such as less than 3.0 wt.%, such as less than 2.0 wt.%, such as less than 1.0 wt.% of primary precipitates. In one or more embodiments, the biodegradable alloy is characterized by being essentially rid of primary precipitates.Primary precipitates such as intermetallic ternary MgZnCa precipitates may precipitate in the initial steps of alloy production which are very hard metal precipitates not easily re-solutionized, and may therefore persist even after thermo-mechanical processing and microstructure refinement. The presence of certain alloy precipitates may bring with them a large difference in redox potentials between the precipitate and the surrounding matrix, composed mainly of magnesium, which causes increased galvanic corrosion rates, and may also lead to ‘pitting’, a term known to those skilled in the field which acts as a stress concentrator in the material. By the foregoing, it is imperativeP6368PC00that the formation of such intermetallic ternary precipitates can be kept to a minimum and if present, that any risk has been sufficiently mitigated. Other binary intermetallic precipitates which may be present in the alloy include one or more of MgZn, Mg5iZn2o, MgZn2, Mg2Ca, or Zn2Zr.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by comprising an amount of ternary MgZnCa primary precipitates, such as wherein the ternary MgZnCa primary precipitates are in one example Mg6Zn3Ca2.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by comprising less than 10 wt.% of ternary MgZnCa primary precipitates, such as less than 5.0 wt.%, such as less than 4.0 wt.%, such as less than 3.0 wt.%, such as less than 2.0 wt.%, such as less than 1.0 wt.% of ternary MgZnCa primary precipitates. In one or more embodiments, the biodegradable alloy is characterized by being essentially rid of ternary MgZnCa primary precipitates.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by primary precipitates having an average size of 20 pm in diameter or less, such as 15 pm or less, such as 10 pm or less, such as 5 pm, 4 pm, 3 pm, 2 pm, .5 pm, 1 pm, or less.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by primary precipitates having an average size of 1 pm or less in diameter.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by ternary MgZnCa primary precipitates having an average size of 20 pm in diameter or less, such as 15 pm or less, such as 10 pm or less, such as 5 pm, 4 pm, 3 pm, 2 pm, .5 pm, 1 pm, or less.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by ternary MgZnCa primary precipitates have an average size of 1 pm or less in diameter.P6368PC00In one or more embodiments of the present disclosure, the formation and / or presence of secondary precipitates may be seen as advantageous, and of particular preference is the presence of coherently bound secondary precipitates, ideally prismatic platelets, which provide the final alloy with increased strength without compromising degradation rate, which may otherwise be seen in some examples of incoherently bound secondary precipitates.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by comprising an amount of secondary precipitates. In one or more embodiments of the present disclosure, the amount of secondary precipitates may represent an amount of one or more of prismatic platelets or basal platelets or <c>-axis rods.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by comprising an amount of prismatic platelets, such as wherein the prismatic platelet particles have an average size of 50 nm or less in diameter, such as 40 nm, such as 30 nm, such as 25 nm, such as 20 nm, such as 15 nm, such as 10 nm or less in diameter.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by prismatic platelet particles have an average size of approximately 10-30 nm in diameter, more preferably a size of approximately 10-20 nm in diameter.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by prismatic platelet particles have a thickness of more than one monolayer, such as at least two atomic layers.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by prismatic platelet particles have a thickness of 2-20 atomic layers, such as 2-15 atomic layers, such as 2-10 atomic layers, such as 2-5 atomic layers.In one or more embodiments of the present disclosure, the biodegradable alloy is characterized by prismatic platelet particles have a thickness of 0.5 nm or more, such as 1 nm or more, such as 1.5 nm or more, such as 2 nm or more.P6368PC00In one or more embodiments of the present disclosure, a composition comprising the biodegradable alloy as described herein is provided within the scope of the present invention.In one or more embodiments of the present disclosure, the alloy is utilized in the manufacture of biodegradable medical implants. The alloys of the present disclosure are characterized by biomechanical properties which make them suitable for applications such as means for fixation of elements to bone, more specifically bone fixation devices, screws, or plates.Also provided within the scope of the present invention is one or more embodiments of the present disclosure relating to a use of the biodegradable alloy, or composition comprising the same, as described herein, in the manufacture of a medical implant, such as a medical implant suitable for use as means for fixation of elements to bone.Also provided within the scope of the present invention is one or more embodiments of the present disclosure relating to a biodegradable medical implant comprising the biodegradable alloy, or composition comprising the same, as described herein.In one or more embodiments of the present disclosure is also provided a method for manufacturing a biodegradable MgZnCaZr quaternary alloy.In one or more embodiments of the present disclosure, the method for manufacturing the alloy includes heat-treating an ingot at a first temperature (T1) between 200 °C and 520 °C to achieve solid solutioning of alloying elements. An optional subsequent heattreatment at higher temperatures (T2) facilitates the dissolution of additional primary precipitate phases and / or eutectic microconstituents forming at higher temperatures. Quenching processes are used to retain the desired microstructure in ‘super-saturated solid solution’ state. Examples include quenching in water, gas, or air stream to room temperature to rapidly stabilize the alloy.In one or more embodiments of the present disclosure, the method for manufacturing the biodegradable alloy according to the present disclosure is characterized by comprising the steps:P6368PC00a. Providing an alloy ingot with an elemental composition comprising at least an amount of Zn, Ca, Zr and Mg;b. A first heat-treatment comprising heating the ingot to a first temperature (T1) between 200 °C and 500 °C and holding for 2 to 30 hours, such as 5 to 30 hours;c. Optionally, a second heat-treatment subsequent to the first heattreatment, comprising heating the ingot to a second temperature (T2) between 400 °C and 520 °C and holding for 2 to 15 hours, such as 5 to 15 hours; andd. Quenching, such as by immersion in water at room temperature, so as to obtain a heat-treated ingot.In one or more embodiments of the present disclosure, the purpose of the first heattreatment at first-temperature (T1) is to obtain a solid solutioning of all elements capable of forming low-temperature eutectic or eutectoid compositions, such as exemplary Mg-Zn eutectics.In one or more embodiments of the present disclosure, the first temperature (T1) is from 200 °C to 500 °C, such as from 200 °C to 225 °C, such as from 225 °C to 250 °C, such as from 250 °C to 275 °C, such as from 275 °C to 300 °C, such as from 300 °C to 325 °C, such as from 325 °C to 350 °C, such as from 350 °C to 375 °C, such as from 375 °C to 400 °C, such as from 400 °C to 450 °C, such as from 450 °C to 500 °C.In one or more embodiments of the present disclosure, the first temperature (T1) is from 200 °C to 350 °C, such as from 200 °C to 325 °C, such as from 250 °C to 350 °C, such as from 250 °C to 325 °C.In one or more embodiments of the present disclosure, the purpose of the second heattreatment at second-temperature (T2) is to obtain a solid solutioning of all elements capable of forming high-temperature eutectic or eutectoid compositions, such as exemplary Mg-Ca eutectics.In one or more embodiments of the present disclosure, the second temperature (T2) is from 400 °C to 550 °C, such as from 400 °C to 425 °C, such as from 425 °C to 450 °C,P6368PC00such as from 450 °C to 475 °C, such as from 475 °C to 500 °C, such as from 500 °C to 520 °C, such as from 520 °C to 550 °C.In one or more embodiments of the present disclosure, the second temperature (T2) is from 425 °C to 520 °C, such as from 450 °C to 520 °C, such as from 400 °C to 520 °C.In one or more embodiments of the present disclosure, the biodegradable alloy obtained by the herein described method is characterized by one or more of a tensile yield strength (TYS) of 120 MPa to 160 MPa, and / or an ultimate tensile strength (UTS) of 120 MPa to 160 MPa, and / or a structural degradation rate in simulated body fluid of less than 6.0 mm / year, such as from 0.3 to 6.0 mm / year.In one or more embodiments of the present disclosure, the biodegradable alloy obtained by the herein described method is characterized by one or more of a tensile yield strength (TYS) of 120 MPa to 350 MPa, and / or an ultimate tensile strength (UTS) of 150 MPa to 350 MPa, and / or a Vickers hardness (HV) of at least 50.In one or more embodiments of the present disclosure, the biodegradable alloy obtained by the herein described method is characterized by one or more of a tensile yield strength (TYS) of 120 MPa to 170 MPa, and / or an ultimate tensile strength (UTS) of 150 MPa to 170 MPa, and / or a Vickers hardness (HV) of at least 60 to 75.The manufacturing method according to the present disclosure in one or more embodiments takes advantage of heat treatment at elevated temperatures followed by rapid quenching to homogenise the alloy forming in it super-saturated solid solution (SSSS). The utilized heat treatment may consist of one or two steps depending on the state of nature and composition of the as-cast alloy, as an example, taking into consideration the amount and species of primary precipitates in the as-cast alloy.The temperature of the first heat treatment is defined by the lowest melting temperature of any phases present in the alloy microstructure in addition to the dominant magnesium matrix phase (the heat treatment temperature should be several degrees Celsius lower than the lowest melting temperature).P6368PC00As an example of an embodiment, if only Mg-Zn based precipitates are present in the microstructure (such as binary MgZn or MgZn2), the heat treatment for the purpose of homogenisation may consist of a single-step heating to 320 °C, holding for several hours and quenching in water to ambient temperature. If however, both Mg-Zn and Mg-Ca based precipitates are present in the microstructure, the heat treatment should comprise at least two steps: a first heating to a temperature (T1) of e.g. 320°C or less and holding for several hours, then heating further to a higher temperature (T2) of e.g.500°C or less and holding for several hours, and finally quenching in water to ambient temperature.It is important to control the solidification and cooling rates to limit precipitation of ternary intermetallic Mg-Zn-Ca precipitates, both primary and secondary. In the present example, this can be achieved with quenching in water, but other media such as oil or liquid nitrogen or air stream are envisioned at also being suitable for the same purpose.In one or more embodiments of the present disclosure, additional steps such as machining, hot extrusion, or artificial aging, or any combinations thereof, may be employed after the quenching step d in order to further modify the alloy’s microstructure and properties. In one or more embodiments of the present disclosure, a subsequent aging step may be incorporated to facilitate and / or improve precipitation hardening and degradation rates to match a specific medical purpose.In one or more embodiments of the present disclosure, herein described manufacturing method is characterized by further comprising at least one of the following steps subsequent to the quenching step d:i. Machining; and / orii. Deformation processing; and / oriii. Aging.In one or more embodiments of the present disclosure, the step of machining, subsequent to step d of the manufacturing method, comprises machining of the heat-treated ingot into a billet and / or workpiece.In one or more embodiments of the present disclosure, the step of deformation processing subsequent to step d of the manufacturing method is characterized byP6368PC00comprising and / or referring to deformation processing of a workpiece, such as of the heat-treated ingot at elevated temperatures. This step may affect both shape of a workpiece and material microstructure along with texture.Deformation processing may in one embodiment comprise one or more of traditional processes such as extrusion, rolling, drawing, or forging, each of which may include elongating the workpiece and / or ingot in at least one direction concomitant with a reduction in at least one of the other directions. In one or more embodiments of the present disclosure, the step of deformation processing does not comprise extrusion processing.In one or more embodiments of the present disclosure, one deformation cycle may be described as the accumulated equivalent strains of one or more of the following:up to e=2.0, 3.0, 4.0, or 5.0 in extrusion, including any 0.10 value therein between;up to e=0.2, 0.225, 0.25, 0.275, 0.30 in rolling, including any 0.01 value therein between; andup to e=0.10, 0.15, or 0.20 in drawing, including any 0.01 value therein betweenOne deformation cycle may in one or more embodiments of the present disclosure be limited to the accumulated equivalent strains of up to e=3.5 (engineering strains e~97% or elongation X~35) in extrusion, e=0.26 (e~30% or X~1.3) in rolling, and e=0.14 (E~15% or X~1.15) in drawing. If larger changes in a net shape are necessary, heat treatment such as recrystallisation may be used to ‘reset’ microstructure and to repeat the cycle.In one or more embodiments of the present disclosure, the step of aging subsequent to step d of the manufacturing method may comprise both natural aging and artificial aging. As used herein, the term “artificial aging” refers to any aging (such as storage) taking place under one or more of non-ambient conditions, in particular non-ambient temperature. By extension, the term “natural aging” refers to aging processes (such as storage) taking place under strictly ambient conditions, strictly ambient conditions here generally referring to room temperature, atmospheric air and pressure.P6368PC00In one or more embodiments of the present disclosure, the step of aging subsequent to step d of the manufacturing method is characterized by comprising subjecting the heat-treated ingot or workpiece to a third temperature (T3) which is from ambient to 200°C for extended periods of time (hours, days, weeks), such as also including natural aging occurring during the product shelf-life. This processing step may be implemented for further material strengthening without compromising degradation rate due to the formation of Mg-Zn based secondary precipitates coherently bound to the matrix.In one or more embodiments of the present disclosure, the step of deformation processing, subsequent to step d of the manufacturing method, comprises extrusion, which in one example may be direct extrusion into rods with various cross-section profiles, wherein the extrusion is performed subject to one or more of the following parameters:i) an extrusion temperature above ambient, such as from ambient to 350 °C, or an extrusion temperature above 250 °C, such as from 250 °C to 350 °C, more preferably at 325 °C;ii) a ram speed of 0.1 to 1.0 mm / s or more, such as 0.1 mm / s, 0.2 mm / s, 0.3 mm / s, 0.4 mm / s, 0.5 mm / s, 0.6 mm / s, 0.7 mm / s, 0.8 mm / s, 0.9 mm / s, 1.0 mm / s or more; preferably 0.5 mm / s; andiii) an extrusion ratio of 1 :10 to 1 :50 or more, such as 1:10, 1 :15, 1 :20, 1 :25, 1 :30, 1 :35, 1 :40, 1 :45, 1 :50 or more, preferably 1 :25.In one or more embodiments of the present disclosure, the step of deformation processing does not involve an extrusion step. In one or more embodiments, the step of deformation processing may be left entirely out of the manufacturing process. Within the field of alloy processing, extrusion is often employed in alloy manufacturing as a means for improving strength of a workpiece. However as demonstrated herein, it has been shown that employing the presently disclosed method and alloy composition, samples with extrusion-level strengths can be obtained even in the absence of an extrusion step. Furthermore, these non-extruded samples have the advantage of not only being more cost effective to produce (on account of not needing an extrusion step), but also demonstrate superior corrosion properties (i.e. lower corrosion rates and less pitting).P6368PC00In one or more embodiments of the present disclosure, the step of aging, subsequent to step d of the manufacturing method, comprises artificial aging at a third heattreatment of the alloy in atmospheric air or in a liquid media, such as exemplary silicone oil, mineral oil or an equivalent non-interacting oil at a third temperature (T3) between 150 °C and 200 °C in combination holding for 10 to 60 hours, so as to obtain an artificially aged alloy, preferably wherein the third heat-treatment is performed between 160 °C to 180 °C in combination with a holding time of 10 to 50 hours.In one or more embodiments of the present disclosure, the step of aging, subsequent to step d of the manufacturing method may comprise artificial aging comprising the use of atmospheric air or a liquid media, such as exemplary silicone oil, mineral oil or an equivalent non-interacting oil. In one or more embodiments of the present disclosure, the heat-treated ingot or workpiece is aged in a silicone oil at a temperature (T3) from 100 °C to 150 °C for 10 to 80 hours or even longer, such as from 140 °C to 150 °C for 20 to 60 hours.In one or more embodiments of the present disclosure, the step of aging, subsequent to step d of the manufacturing method is artificial aging performed in atmospheric air or in a liquid media, such as exemplary silicone oil, mineral oil or an equivalent noninteracting oil at a temperature (T3) from above ambient to 100 °C for 30-100 hours or even longer. In particular, aging performed in silicone oil at a temperature (T3) between 40 °C and 100 °C for at least 10 to 26 weeks, and is preferably done at 60 °C to 70 °C for 15 to 20 weeks or more.In one or more embodiments of the present disclosure, the step of aging, subsequent to step d of the manufacturing method is artificial aging performed in atmospheric air or in a liquid media, such as exemplary silicone oil, mineral oil or an equivalent noninteracting oil at a temperature (T3) between ambient and 150 °C for 60 hours to 1 year. In particular, aging performed in silicone oil at a temperature (T3) between 60 °C to 100 °C for 600 to 1600 hours is preferred in some embodiments.In one or more embodiments of the present disclosure, the step of aging, subsequent to step d of the manufacturing method is natural aging performed in atmospheric air or in a liquid media, such as exemplary silicone oil, mineral oil or an equivalent non-P6368PC00interacting oil at a temperature (T3) equivalent to ambient (room temperature) for 26 (0.5 year) to 80 weeks (1.5 years), such as for more than 52 weeks.In one or more embodiments of the present disclosure, the third temperature (T3) is from ambient to 200 °C, such as from ambient to 180 °C, such as from 50 °C to 150 °C, such as from 60 °C to 140 °C, such as from 80 °C to 120 °C, such as from 90 °C to 110 °C, such as 100 °C. In one or more embodiments, the step or aging comprises holding the alloy at the third temperature (T3) for a time of 10 hours to 1.5 years, such as 60 hours to 1 year, such as 600 hours to 1600 hours.In particular, the media, such as oil, preferably covers the ingot and / or workpiece during aging, such as the workpiece is fully submerged in the media during aging.It is generally understood that while the present disclosure has been described in detail in connection with only a limited number of embodiments or aspects, it should be readily understood that the present disclosure is not limited to such disclosed embodiments or aspects. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate in scope with the present disclosure. Additionally, while various embodiments or aspects of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments or aspects or combinations of the various embodiments or aspects. Accordingly, the present disclosure is not to be seen as limited by the foregoing description.The invention is here below illustrated by way of the following examples.ExamplesMaterials and methodsThe materials exemplified herein are MgZnCaZr quaternary biodegradable alloys comprising Mg (balance), 0.15 wt.% Ca, 0.15 wt.% Zr, and Zn in the range of 3.1 wt.% to 4.1 wt.%. The exemplified herein may be referred to by sample names ‘High-Zn’, ‘Medium-Zn’ or ‘Low-Zn’ samples, or simply ‘High’, ‘Medium’, ‘Low’. Each sample is characterized by comprising the Mg, Ca and Zr amounts as listed hereabove.P6368PC00Furthermore, the samples comprise either 3.1 wt.% Zn (Low), 3.7 wt.% (Medium), or 4.1 wt.% (High).The as-cast alloys were produced by adding zinc and calcium in pure form to high-purity magnesium (Fe below 30 ppm), and also adding zirconium via a master Mg-33Zr alloy. Melting of the alloys was performed in a graphite crucible in a resistance-heating furnace. The material melting, alloying, casting and solidification were carried out in a protective gas (Ar + 1 vol. % SF6) atmosphere to produce as-cast alloys.Heat treatment of the as-cast alloys for solid solutioning was carried out under protective gas (pure Ar) atmosphere in two steps. Step I entailed subjecting the alloy to a temperature of 320°C for 12 hours. Step II entailed subjecting the alloy obtained from Step I to a temperature of 470°C for 10 hours followed by quenching in water. This two-step heat treatment is also herein referred to as ‘normalisation’ and / or ‘homogenisation’, and the material state after the treatment may be referred to as ‘super saturated solid solution’ (SSSS).Extrusion of selected samples was carried out by direct extrusion with a ram speed of 0.5 mm / s, the ratio of final : initial cross-section area 1 :25, in a tool set preheated to 325°C.Aging of the samples (which were optionally extruded) was also done by heat treatments. In the examples of the present disclosure, heat treatment for aging was carried out at 60°C, 100°C, 150°C or 180°C in an oil-bath furnace with a synthetic silicone-based oil as a protective heating medium. During aging, specimens were extracted from the furnace for hardness measurements at regular intervals of aging at 180°C, 150°C, 100°C or 60°C, respectively. Shorter intervals were used on approach to expected maximum peak hardness, i.e. peak-aged (PA) condition. The PA conditions were determined retroactively upon finishing aging after at least three successive measurements demonstrating a decreasing trend in hardness values. The experimental values of hardness as a function of time were fitted with a third-order polynomial function, and the local maximum value was recorded as the PA condition.Final specimen preparation was carried out in several steps. First, 10 mm diameter rods were cut from the as-cast and solid-solution treated samples along the castingP6368PC00direction at least 5 mm from the side surface using electric-discharge machining (EDM). As-extruded rod samples already had 10 mm diameter. The rods were then cut into disks. After cutting, the disks were ground on both sides to the thickness of approximately 1 mm using SiC paper in 1 mm steps of decreasing grain size down to a final 4000 grit giving final roughness on the specimen surface of approximately 5 pm. Such a surface finish was also used for degradation / corrosion testing, for which the final grinding step was performed as close as possible to the start of immersion test to minimize the effect of atmospheric corrosion. The thickness and diameter of each specimen were measured with 0.1 pm accuracy. The specimens were weighed with accuracy 0.01 mg . This was done prior to and after degradation / corrosion testing. Specimens for hardness testing were further polished using water-free lubricants with diamond suspensions down to 0.25 pm particle sizes. Specimens for SEM examination were further polished using colloidal silica suspension.Material hardness was evaluated using Vickers (HV) method following ASTM E92-23 in Struers Duramin 40 tester with 100 g force and 15 s dwell time. At least ten indentations were made on each specimen with a distance between indents of at least three diagonals of the indenter imprint, and average values were reported.Experimentally obtained HV values were converted to the material Yield Strength following Pintaude (2022). Both HV and yield strength values were recorded.Degradation testing was performed according to standards: ASTM G1-03 and ASTM G31 -21 using Applikon AppliFlex ST 3L bioreactor for specimen’s immersion. The immersion medium was Hank’s Balanced Salt Solution (HBSS) modified to contain 1.6 g / L sodium bicarbonate (NaHCOs) and 0.265 g / L calcium chloride dihydrate (CaCl2'2H2O). During the immersion, the medium temperature and pH level were maintained at 37±0.5 °C and pH 7.4±0.1 using a heating mantle wrapped around the reactor and sparging CO2 gas, respectively. After immersion, corrosion products were removed using CrOs based solution according to ASTM G1-03. The specimens were cleaned individually to minimise cross contamination. Afterwards, the specimens were balanced again and corrosion rates were calculated according to ASTM G1-03.Optical microscopy was carried out using digital optical microscope Keyence VHX-6000 equipped with polarised light.P6368PC00Scanning electron microscopy (SEM) was carried out using an FEI Quanta 200 MKII W-filament gun at accelerating voltages up to 20 keV. Unless otherwise specified, micrographs were acquired using back-scatter electron (BSE) imaging mode.Example 1 - homogenization of as-cast alloys.Initial billet is produced from liquid melt of desired chemical composition and purity by casting into permanent graphite moulds as described above (as-cast alloy).Microstructure in the alloy at this stage would typically consist of matrix grains and primary precipitates agglomerated along grain boundaries and triple junctions of the matrix grains. Such a microstructure is shown as an example in Fig. 1a and schematically in Fig. 2a. It is typically undesirable from performance characteristics standpoint due to the large amount of primary precipitates decorating grain boundaries.Therefore, afterwards the billets are heat-treated in two steps: (i) at a temperature of 300-320 °C for 10-15 hours to ensure solid-solutioning of all elements potentially forming low-temperature eutectic or eutectoid compositions, i.e. Mg-Zn, and (ii) immediately after at 450-520 °C for 6-12 hours to ensure solid-solutioning of all elements potentially forming higher-temperature eutectic or eutectoid compositions, i.e. Mg-Ca, and finally cooled to room temperature in water (quenched). This process flow is shown schematically in Fig. 6, first column.As a result of such a fabrication route, we obtain the material with• Rather homogeneous microstructure predominantly consisting of SSSS matrix grains approximately 60 iim in average diameter, as illustrated in Fig. 1 b-d.Storage of the material in this condition at ambient temperature may also lead to natural aging and the formation of secondary precipitates shown in Fig. 3a, b. • Vickers hardness of at least HV 55, see Table 1, which is approximately equivalent to a tensile yield strength (TYS) of 126 MPa, and• a degradation rate of 1.34 mm / y or lower in Hanks Balanced Salt Solution (HBSS), see Table 3, which should be even lower in biological media.Example 2 - homogenization and extrusion of as-cast alloys.The material is first fabricated in the same manner as Example 1.P6368PC00Afterwards, the ingots were machined and direct extruded at 325°C, ram speed of 0.5 mm / s and extrusion ratio 1 :25 to 10 mm diameter rods. This process flow is shown schematically in Fig. 6, second column.As a result of such a fabrication route, we obtained the material with• Rather homogeneous microstructure predominantly consisting of matrix grains approximately 6 iim in diameter, as illustrated in Fig. 1 e,f and 3g. Secondary precipitates incoherently bound to the matrix can be seen as small white-dot features in Fig. 1f and black-round features in Fig. 3g.• Vickers hardness of at least HV 61.3, see Table 2, which is approximately equivalent to a tensile yield strength (TYS) of 141 MPa, and• a degradation rate of 0.88 mm / y or lower in Hanks Balanced Salt Solution (HBSS), see Table 4, which should be even lower in biological media.Example 3 - homogenization and peak- aging of as-cast alloys.The material is first fabricated in the same manner as Example 1.Afterwards, bars of 10 mm diameter were machined from the ingots as described in the methods section, and artificially aged in silicone oil bath, exemplary at 180°C for 16-18 hours. This process flow is shown schematically in Fig. 6, third column.As a result of such a fabrication route, we obtained the material with• Rather homogeneous microstructure predominantly consisting of SSSS matrix grains and secondary precipitates shown in Fig. 3e,f.• Vickers hardness of at least HV 68.3, see Table 1 , which is approximately equivalent to a tensile yield strength (TYS) of 157 MPa, and• a degradation rate of 0.80 mm / y or lower in Hanks Balanced Salt Solution (HBSS), see Table 3, and even lower in biological media.Example 4 - homogenization, extrusion and peak-aging of as-cast alloys.This material is first fabricated in the same manner as Example 2.Finally, the extruded rods were artificially aged in silicone oil bath, exemplary at 180°C for 16-18 hours. This process flow is shown schematically in Fig. 6, fourth column.P6368PC00As a result of such a fabrication route, we obtained the material with• Vickers hardness of at least HV 64.8, see Table 2, which is approximately equivalent to a tensile yield strength (TYS) of 150 MPa, and• a degradation rate of 0.56 mm / y or lower in Hanks Balanced Salt Solution (HBSS), see Table 4, which should be even lower in biological media.Table 1 - Vickers hardness (HV) in as-homogenised and peak-aged (PA) alloys with varying levels of zinc content (low / medium / high) along with time (t) necessary to achieve the PA condition.Table 2 - Vickers hardness (HV) in as-extruded and peak-aged (PA) alloys with varying levels of zinc content (low / medium / high) along with time (t) necessary to achieve the PA condition.Table 3 - Corrosion rate (CR) in as-homogenised and peak-aged (PA) alloys with varying levels of zinc content (low / medium / high) after immersion in Hank’s Balanced Salt Solution (HBSS) at 37°C for 7 days along with time (t) necessary to achieve the PA condition.P6368PC00Table 4 - Corrosion rate (CR) in as-extruded and peak-aged (PA) alloys with varying levels of zinc content (low / medium / high) after immersion in Hank’s Balanced Salt Solution (HBSS) at 37°C for 7 days along with time (t) necessary to achieve the PA condition.Table 5 - Corrosion rate (CR) in as-homogenised and peak-aged (PA) alloys with varying levels of zinc content (low / medium / high) after immersion in Hank’s Balanced Salt Solution (HBSS) at 37°C for 7 days along with time (t) necessary to achieve the PA condition.The examples demonstrate that rather broad spectrum of performance characteristics can be obtained in the alloy through thermo-mechanical processing. Deeper analysis of the homogenised alloy reveals rather consistent and therefore reliable trends in the evolution of performance characteristics after artificial aging. Namely (see Table 1), Vickers hardness of the homogenized samples increases with the increase of Zn content, both for the non-peak aged and the peak-aged samples (obtained in Examples 1 and 3, respectively). Furthermore, it can be observed that aging the homogenized samples uniformly leads to an increase in hardness. For the homogenized and peakaged samples, the combination of high-Zn content and peak-aging temperature of 150 °C leads to the maximum value of HV 79, representing almost 30% increase in hardness of the material. For comparison, the homogenized and extruded alloys only experience an average of less than 8% increase in strength upon aging (maximum observed 14%).P6368PC00In particular, it is found surprising that the peak-aged hardness of the extruded samples does not exceed the peak-aged hardness of the homogenized but non-extruded alloy samples.The results may be rationalized in terms of the competing processes of hardening obtained by precipitation and Zr-mediated microstructure grain refinement as opposed to extrusion, which by virtue of being a hot deformation process provides strain hardening through grain refinement, but also is at this point thought to destroy the fine precipitate structure obtained in the homogenization step.Moreover, further analysis of specimen surfaces after immersion testing in Fig. 5 clearly reveals heterogeneous degradation in the extruded alloy whereas a homogenous degradation is observed for the homogenized sample (reflecting chemically homogenous microstructure).In the extruded samples, a significant number of pits visible as dark spots can also be seen in all the extruded alloys with a particularly large number in the high-Zn extruded alloy. By contrast, the specimens in the homogenised alloys have on their surfaces rather homogeneously passivated film from degradation products with virtually no pits. Within biodegradable orthopaedic implants it is desirable to have a consistent and homogenous degradation process to ensure stability and predictability for both patient and practitioner.The complex of properties in the materials produced in examples 1 and 2 should be considered as ‘intermediate’, which can already be usable as it is. Further improvement in material performance characteristics can be achieved by artificial (peak) aging, as demonstrated in the examples 3 and 4. The later examples allow for provision of alloys suitable for fulfilling demands for the majority of applications intended for biodegradable orthopaedic implants.Items1. A biodegradable magnesium-based quaternary alloy characterized by comprising or consisting essentially of magnesium (Mg), calcium (Ca), zinc (Zn), and zirconium (Zr).P6368PC002. The alloy according to any one of the preceding items, characterized by comprising:a. 3.0 (±0.2) wt.% to 4.0 (±0.2) wt.% of Zn;b. 0.10 (±0.05) wt.% to 0.30 (±0.05) wt.% of Ca;c. 0.001 (±0.05) wt.% to 0.30 (±0.05) wt.% of Zr;d. Mg (base),3. The alloy according to any one of the preceding items, characterized by comprising:a. 3.0 (±0.1 ) wt.% to 4.0 (±0.1 ) wt.% of Zn;b. 0.10 (±0.02) wt.% to 0.30 (±0.02) wt.% of Ca;c. 0.15 (±0.02) wt.% to 0.30 (±0.02) wt.% of Zr;d. Mg (base),4. The alloy according to any one of the preceding items, characterized by comprising:a. 3.0 (±0.1 ) wt.% to 4.0 (±0.1 ) wt.% of Zn;b. 0.15 (±0.02) wt.% of Ca;c. 0.15 (±0.02) wt.% of Zr;d. Mg (base),5. The alloy according to any one of the preceding items, characterized by comprising 0.15 wt.% of Ca.6. The alloy according to any one of the preceding items, characterized by comprising 0.15 wt.% of Zr.7. The alloy according to any one of the preceding items, characterized by comprising 3.1 wt.% to 3.7 wt.% of Zn.8. The alloy according to any one of the preceding items, characterized by not comprising any amount of rare-earth elements and / or rare-earth metals.9. The alloy according to any one of the preceding items, characterized by a structural degradation rate of 6 mm / year or lower.P6368PC0010. The alloy according to any one of the preceding items, characterized by a structural degradation rate of 6 mm / year or lower, such as 5 mm / year or lower, such as 4 mm / year or lower, such as 3.5 mm / year or lower, such as 3 mm / year or lower, such as 2.5 mm / year or lower, such as 2 mm / year or lower, such as 1.5 mm / year or lower, such as 1 mm / year or lower, such as 0.5 mm / year or lower, such as 0.3 mm / year or lower.11. The alloy according to any one of the preceding items, characterized by a structural degradation rate of 0.5 to 2.0 mm / year, such as 0.5 to 1.5 mm / year.12. The alloy according to any one of the preceding items, wherein structural degradation is determined using simulated body fluid such as Hanks Balanced Salt Solution (HBSS) or another buffered salt solution.13. The alloy according to any one of the preceding items, characterized by a tensile yield strength (TYS) ranging from 100 MPa to 250 MPa.14. The alloy according to any one of the preceding items, wherein the tensile yield strength (TYS) ranges from 100 MPa to 250 MPa, such as 100 MPa to 110 MPa, such as 110 MPa to 120 MPa, such as 120 MPa to 130 MPa, such as 130 MPa to 140 MPa, such as 140 MPa to 150 MPa, such as 150 MPa to 160 MPa, such as 160 MPa to 170 MPa, such as 170 MPa to 180 MPa, such as 180 MPa to 200 MPa, such as 200 MPa to 250 MPa.15. The alloy according to any one of the preceding items, wherein the tensile yield strength (TYS) ranges from 120 MPa to 170 MPa.16. The alloy according to any one of the preceding items, wherein the tensile yield strength (TYS) is 150 ±10 MPa.17. The alloy according to any one of the preceding items, characterized by an ultimate tensile strength (UTS) ranging from 150 MPa to 550 MPa.P6368PC0018. The alloy according to any one of the preceding items, wherein the ultimate tensile strength (UTS) ranges from 150 MPa to 550 MPa, such as 150 MPa to 160 MPa, such as 160 MPa to 180 MPa, such as 180 MPa to 200 MPa, such as 200 MPa to 250 MPa, such as 250 MPa to 300 MPa, such as 300 MPa to 400 MPa, such as 400 MPa to 550 MPa, such as 300 MPa to 550 MPa.19. The alloy according to any one of the preceding items, wherein the ultimate tensile strength (UTS) ranges from 150 MPa to 250 MPa.20. The alloy according to any one of the preceding items, wherein the ultimate tensile strength (UTS) is 210 ±10 MPa.21. The alloy according to any one of the preceding items, characterized by a Vickers hardness (HV) of at least 50.22. The alloy according to any one of the preceding items, characterized by a Vickers hardness (HV) of at least 50 or more, such as 55 or more, such as 60 or more, such as 65 or more, such as 70 or more, such as 75 or more.23. The alloy according to any one of the preceding items, characterized by a Vickers hardness (HV) from 40 to 90, such as from 50 to 60, such as from 60 to 70, such as from 70 to 80, such as from 55 to 65, such as from 65 to 75.24. The alloy according to any one of the preceding items, wherein the alloy is essentially free of other 3d transition metals than Zn.25. The alloy according to any one of the preceding items, characterized by a microstructure, such as a homogenous microstructure, of matrix grains having a diameter from 0.2 pm to 100 pm, such as from 0.2 pm to 2 pm, such as from 2 pm to 4 pm, such as from 4 pm to 6 pm, such as from 6 pm to 8 pm, such as from 8 pm to 10 pm, such as from 10 pm to 15 pm, such as from 15 pm to 30 pm, such as from 30 pm to 50 pm, such as from 50 pm to 75 pm, such as from 75 pm to 100 pm.P6368PC0026. The alloy according to any one of the preceding items, characterized by comprising an amount of ternary MgZnCa primary precipitates, such as wherein the ternary MgZnCa primary precipitates are Mg6Zn3Ca2.27. The alloy according to any one of the preceding items, characterized by comprising less than 10 wt.% of ternary MgZnCa primary precipitates, such as less than 5.0 wt.%, such as less than 4.0 wt.%, such as less than 3.0 wt.%, such as less than 2.0 wt.%, such as less than 1.0 wt.% of ternary MgZnCa primary precipitates.28. The alloy according to any one of the preceding items, wherein the ternary MgZnCa primary precipitates have a size of 5 pm in diameter or less, such as 4 pm, such as 3 pm, such as 2 pm, such as 1.5 pm, such as 1 pm or less.29. The alloy according to any one of the preceding items, wherein the ternary MgZnCa primary precipitates have a size of 1 pm or less in diameter.30. The alloy according to any one of the preceding items, characterized by comprising an amount of secondary precipitates, such as in the form of prismatic platelets particles.31. The alloy according to any one of the preceding items, wherein the prismatic platelet particles have a size of 50 nm or less in diameter, such as 40 nm, such as 30 nm, such as 25 nm, such as 20 nm, such as 15 nm, such as 10 nm or less in diameter.32. The alloy according to any one of the preceding items, wherein the prismatic platelet particles have a size of approximately 10-30 nm in diameter, more preferably a size of approximately 10-20 nm in diameter.33. The alloy according to any one of the preceding items, wherein the prismatic platelet particles have a thickness of more than one monolayer, such as at least two atomic layers.P6368PC0034. The alloy according to any one of the preceding items, wherein the prismatic platelet particles have a thickness of 0.5 nm or more, such as 1 nm or more, such as 1.5 nm or more, such as 2 nm or more.35. A composition comprising the alloy according to any one of the preceding items.36. Use of the alloy according to any one of the preceding items, or the composition according to item 35, in the manufacture of a medical implant.37. A biodegradable medical implant comprising the alloy according to any one of the preceding items.38. A method for manufacturing a MgZnCaZr quaternary alloy comprising the steps:a. Providing an alloy ingot with an elemental composition according to any one of the preceding items;b. A first heat-treatment comprising heating the ingot to a first temperature (T 1 ) between 200 °C and 500 °C and holding for 5 to 30 hours such as to obtain a solid solutioning of all elements capable of forming low- temperature eutectic compositions;c. Optionally, a second heat-treatment subsequent to the first heattreatment, comprising heating the ingot to a second temperature (T2) between 400 °C and 500 °C and holding for 5 to 15 hours such as to obtain a solid solutioning of all elements capable of forming high- temperature eutectic compositions; andd. Quenching, such as by immersion in water at room temperature.39. The method according to any one of the preceding items, wherein the quaternary alloy is characterized by a tensile yield strength (TYS) of 120 MPa to 160 MPa and / or a structural degradation rate in simulated body fluid of less than 6 mm / year.40. The method according to any one of the preceding items, further comprising at least one of the following steps subsequent to the quenching step d:P6368PC00a. Machining; and / orb. Deformation processing; and / orc. Aging.41. The method according to any one of the preceding items, wherein the machining step subsequent to step d comprises machining of the heat-treated ingot into a billet.42. The method according to any one of the preceding items, wherein the deformation processing step subsequent to step d comprises one or more of extrusion, rolling, drawing, or forging.43. The method according to any one of the preceding items, wherein the deformation processing step subsequent to step d comprises extrusion, such as direct extrusion into rods, wherein the extrusion is performed subject to the following parameters:a. a temperature above ambient, such as between 300 °C to 350 °C, more preferably at 325 °C;b. a ram speed of 0.1 to 1.0 mm / s or more, such as 0.1 mm / s, 0.2 mm / s, 0.3 mm / s, 0.4 mm / s, 0.5 mm / s, 0.6 mm / s, 0.7 mm / s, 0.8 mm / s, 0.9 mm / s, 1.0 mm / s; preferably 0.5 mm / s; andc. extrusion ratio of 1 :10 to 1 :50 or more, such as 1 :10, 1 :15, 1 :20, 1 :25, 1 :30, 1 :35, 1 :40, 1 :45, 1 :50, preferably 1 :25.44. The method according to any one of the preceding items, wherein the method does not comprise an extrusion, or any other deformation processing step as part of the manufacturing method.45. The method according to any one of the preceding items, wherein the aging step subsequent to step d comprises a third heat-treatment of the alloy at a third temperature (T3) between 100 °C and 200 °C and holding for 10 to 1600 hours such as to obtain an artificially aged alloy, preferably wherein the third heat-treatment is performed between 150-180 °C at a holding time of 15-45 hours.P6368PC0046. The method according to any one of the preceding items, wherein the aging step subsequent to step d comprises storage at room-temperature or at a temperature between 50-60 °C for at least 1 week, such as 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks.ReferencesJ. Hofstetter, M. Becker, E. Martinelli, A.M. Weinberg, B. Mingler, H. Kilian, S.Pogatscher, P.J. Uggowitzer, J.F. Loftier, High-Strength Low-Alloy (HSLA) Mg-Zn-Ca Alloys with Excellent Biodegradation Performance, JOM 66(4) (2014) 566-572.P. Holweg, L. Berger, M. Cihova, N. Donohue, B Clement, U. Schwarze, N.G. Sommer, G. Hohenberger, J.J.J.P. van den Beucken, F. Seibert, A. Leithner, J.F. Loftier, A.M. Weinberg, A lean magnesium-zinc-calcium alloy ZX00 used for bone fracture stabilization in a large growing-animal model, Acta Biomaterialia 113 (2020) 646-659J.-F. Nie, Precipitation and Hardening in Magnesium Alloys, Metallurgical and Materials Transactions A 43(11 ) (2012) 3891 -3939.G. Pintaude, Hardness as an indicator of material strength: a critical review. Critical Reviews in Solid State and Materials Sciences (2022), 1-19.Items 21. A biodegradable magnesium-based alloy characterized by comprising:a. 3.0 (±0.2) wt.% to 4.0 (±0.2) wt.% of Zn;b. 0.10 (±0.05) wt.% to 0.30 (±0.05) wt.% of Ca;c. 0.10 (±0.05) wt.% to 0.30 (±0.05) wt.% of Zr; andd. Mg (base).2. The biodegradable alloy according to the preceding items, characterized by comprising:a. 3.0 (±0.1 ) wt.% to 4.0 (±0.1 ) wt.% of Zn;b. 0.10 (±0.02) wt.% to 0.30 (±0.02) wt.% of Ca;c. 0.15 (±0.02) wt.% to 0.30 (±0.02) wt.% of Zr;P6368PC00d. Mg (base),3. The biodegradable alloy according to any one of the preceding items, characterized by comprising:a. 3.0 (±0.1 ) wt.% to 4.0 (±0.1 ) wt.% of Zn;b. 0.15 (±0.02) wt.% of Ca;c. 0.15 (±0.02) wt.% of Zr;d. Mg (base),4. The biodegradable alloy according to any one of the preceding items, characterized by comprising less than 0.01 wt.% of rare-earth elements, further wherein the alloy characterized as essentially free of other 3d transition metals than Zn.5. The biodegradable alloy according to any one of the preceding items, characterized by a structural degradation rate of 6 mm / year or lower as determined in simulated body fluid in accordance with ASTM G31.6. The biodegradable alloy according to any one of the preceding items, characterized by one or more:a. a tensile yield strength (TYS) ranging from 120 MPa to 350 MPa; b. an ultimate tensile strength (UTS) ranging from 150 MPa to 350 MPa; c. a Vickers hardness (HV) of at least 50 as determined in accordance with ASTM E92.7. The biodegradable alloy according to any one of the preceding items, characterized by one or more:a. a tensile yield strength (TYS) ranging from 120 MPa to 170 MPa; b. an ultimate tensile strength (UTS) ranging from 150 MPa to 170 MPa; c. a Vickers hardness (HV) of 60 to 75 as determined in accordance with ASTM E92.P6368PC008. The biodegradable alloy according to any one of the preceding items, characterized by comprising less than 2.0 wt.% of ternary Mg6Zn3Ca2 primary precipitates, such as less than 1.0 wt.% of ternary Mg6Zn3Ca2 primary precipitates, said primary precipitates characterized by a diameter size of 20 pm in diameter or less.9. Use of the biodegradable alloy according to any one of the preceding items in the manufacture of an orthopaedic biodegradable implant.10. A biodegradable medical implant comprising the biodegradable alloy according to any one of the items 1 to 8.11. A method for manufacturing a MgZnCaZr quaternary alloy comprising the steps:a. providing, such as in the form of an ingot, an alloy with an elemental composition according to any one of items 1 to 8;b. a first heat-treatment comprising heating the provided alloy to a first temperature (T1) which is between 200 °C and 350 °C and holding for 5 to 30 hours;c. optionally, a second heat-treatment subsequent to the first heattreatment, comprising heating the alloy to a second temperature (T2) between 400 °C and 520 °C and holding for 5 to 15 hours; and d. quenching, such as by immersion in water at room temperature.12. The method according to item 11 , wherein the first heat-treatment is such as to provide a solid solutioning of all elements capable of forming low-temperature eutectic or eutectoid compositions, and wherein the second heat-treatment is such as to provide a solid solutioning of all elements capable of forming high- temperature eutectic or eutectoid compositions.13. The method according to any one of items 11 to 12, further comprising at least a step of aging subsequent to the quenching step d, further wherein said aging step subsequent to step d comprises a third heat-treatment of the alloy at a third temperature (T3) between 100 °C and 200 °C and holding for 10 to 1600 hours such as to obtain an aged alloy, preferably wherein the third heattreatment is performed between 150-180 °C at a holding time of 15-45 hours.P6368PC0014. The method according to any one of items 11 to 13, wherein the quaternary alloy is characterized by a tensile yield strength (TYS) of at least 120 MPa and a structural degradation rate in simulated body fluid of less than 6 mm / year as determined in accordance with ASTM G31 -21 , such as is characterized by a tensile yield strength (TYS) of at least 150 MPa and a structural degradation rate in simulated body fluid of less than 3 mm / year as determined in accordance with ASTM G31 -21.15. The method according to any one of items 11 to 14, wherein the method does not comprise a step of deformation processing such as extrusion.

Claims

P6368PC00Claims1. A biodegradable magnesium-based alloy characterized by comprising:a. 2.8 wt.% to 4.2 wt.% of Zn;b. 0.05 wt.% to 0.20 wt.% of Ca;c. 0.05 wt.% to 0.35 wt.% of Zr; andd. optionally less than 0.05 wt.% of each of any unspecified element;wherein the remainder of the alloy is magnesium.

2. The alloy according to any claim 1 , characterized by comprising:a. 2.9 wt.% to 4.1 wt.% of Zn;b. 0.10 wt.% to 0.20 wt.% of Ca;c. 0.05 wt.% to 0.20 wt.% of Zr; andd. optionally less than 0.05 wt.% of each of any unspecified element;wherein the remainder of the alloy is magnesium.

3. The alloy according to any one of the preceding claims, characterized by comprising 0.15 ±0.02 wt.% of Ca.

4. The alloy according to any one of the preceding claims, characterized by comprising 0.15 ±0.02 wt.% of Zr.

5. The alloy according to any one of the preceding claims, characterized by consisting of:a. 2.9 wt.% to 4.1 wt.% of Zn;b. 0.13 wt.% to 0.17 wt.% of Ca;c. 0.13 wt.% to 0.17 wt.% of Zr;d. optionally less than 0.05 wt.% of each of any unspecified element;wherein the remainder of the alloy is magnesium,6. The alloy according to any one of the preceding claims, characterized by comprising 3.1 wt.% to 3.7 wt.% of Zn.

7. The alloy according to any one of the preceding claims, characterized by comprising less than 0.01 wt.% of rare-earth elements, optionally furtherP6368PC00wherein the alloy is characterized as essentially free of other 3d transition metals than Zn.

8. The alloy according to any one of the preceding claims, characterized by not comprising any amount of rare-earth elements and / or rare-earth metals.

9. The alloy according to any one of the preceding claims, characterized by not comprising any amount of manganese.

10. The alloy according to any one of the preceding claims, characterized by a structural degradation rate of 6 mm / year or lower as determined in accordance with ASTM G31 -21 for an alloy sample in a simulated body fluid at 37±0.5 °C and pH 7.4±0.1 , wherein the simulated body fluid comprises Hank’s Balanced Salt Solution, wherein the alloy sample is in the form of a disc of approximately 1 mm in thickness and 10 mm diameter, and wherein the simulated body fluid volume to specimen surface ratio is 0.4244 mL / mm2.

11. The alloy according to claim 10, wherein the structural degradation rate is determined based on average values of at least four alloy samples, wherein the alloy samples are mechanically ground on both sides using a manual grinding tool, SiC paper and no lubricants down to P4000 grit, and wherein the simulated body fluid comprises Hank’s Balanced Salt Solution modified to contain 1.6 g / L sodium bicarbonate (NaHCOs) and 0.265 g / L calcium chloride dihydrate (CaCI2-2H2O).

12. The alloy according to any one of claims 10 or 11 , characterized by a structural degradation rate of 6 mm / year or lower, such as 5 mm / year or lower, such as 4 mm / year or lower, such as 3.5 mm / year or lower, such as 3 mm / year or lower, such as 2.5 mm / year or lower, such as 2 mm / year or lower, such as 1.5 mm / year or lower, such as 1 mm / year or lower, such as 0.5 mm / year or lower.

13. The alloy according to any one of the preceding claims 10 to 11 , characterized by a structural degradation rate of 0.3 to 2.0 mm / year, such as 0.3 to 1.5 mm / year.P6368PC0014. The alloy according to any one of the preceding claims, wherein structural degradation is determined using simulated body fluid such as Hanks Balanced Salt Solution (HBSS) or another buffered salt solution.

15. The alloy according to any one of the preceding claims, characterized by a tensile yield strength (TYS) ranging from 100 MPa to 250 MPa.

16. The alloy according to any one of the preceding claims, wherein the tensile yield strength (TYS) ranges from 100 MPa to 250 MPa, such as 100 MPa to 110 MPa, such as 110 MPa to 120 MPa, such as 120 MPa to 130 MPa, such as 130 MPa to 140 MPa, such as 140 MPa to 150 MPa, such as 150 MPa to 160 MPa, such as 160 MPa to 170 MPa, such as 170 MPa to 180 MPa, such as 180 MPa to 200 MPa, such as 200 MPa to 250 MPa.

17. The alloy according to any one of the preceding claims, wherein the tensile yield strength (TYS) ranges from 120 MPa to 170 MPa.

18. The alloy according to any one of the preceding claims, wherein the tensile yield strength (TYS) is 150 ±10 MPa.

19. The alloy according to any one of the preceding claims, characterized by an ultimate tensile strength (UTS) ranging from 150 MPa to 550 MPa.

20. The alloy according to any one of the preceding claims, wherein the ultimate tensile strength (UTS) ranges from 150 MPa to 550 MPa, such as 150 MPa to 160 MPa, such as 160 MPa to 180 MPa, such as 180 MPa to 200 MPa, such as 200 MPa to 250 MPa, such as 250 MPa to 300 MPa, such as 300 MPa to 400 MPa, such as 400 MPa to 550 MPa, such as 300 MPa to 550 MPa.

21. The alloy according to any one of the preceding claims, wherein the ultimate tensile strength (UTS) ranges from 150 MPa to 250 MPa.

22. The alloy according to any one of the preceding claims, wherein the ultimate tensile strength (UTS) is 210 ±10 MPa.P6368PC0023. The alloy according to any one of the preceding claims, characterized by a Vickers hardness (HV) of at least 50 as determined in accordance with ASTM E92-23.

24. The alloy according to any one of the preceding claims, characterized by a Vickers hardness (HV) of at least 50 or more, such as 55 or more, such as 60 or more, such as 65 or more, such as 70 or more, such as 75 or more as determined in accordance with ASTM E92-23.

25. The alloy according to any one of claims 1 to 22, characterized by a Vickers hardness (HV) from 40 to 90, such as from 50 to 60, such as from 60 to 70, such as from 70 to 80, such as from 55 to 65, such as from 65 to 75 as determined in accordance with ASTM E92-23.

26. The alloy according to any one of claims 1 to 14, 19, 20, 23 and 24, characterized by one or more:a. a tensile yield strength (TYS) ranging from 120 MPa to 350 MPa; b. an ultimate tensile strength (UTS) ranging from 150 MPa to 350 MPa; c. a Vickers hardness (HV) of at least 50 as determined in accordance with ASTM E92-23.

27. The alloy according to any one of claims 1 to 21 and 23 to 26, characterized by one or more:a. a tensile yield strength (TYS) ranging from 120 MPa to 170 MPa; b. an ultimate tensile strength (UTS) ranging from 150 MPa to 170 MPa; c. a Vickers hardness (HV) of 60 to 75 as determined in accordance with ASTM E92-23.

28. The alloy according to any one of the preceding claims, wherein the alloy is essentially free of other 3d transition metals than Zn.

29. The alloy according to any one of the preceding claims, characterized by a microstructure, such as a homogenous microstructure, of matrix grains having aP6368PC00diameter from 0.2 pm to 100 pm, such as from 0.2 pm to 2 pm, such as from 2 pm to 4 pm, such as from 4 pm to 6 pm, such as from 6 pm to 8 pm, such as from 8 pm to 10 pm, such as from 10 pm to 15 pm, such as from 15 pm to 30 pm, such as from 30 pm to 50 pm, such as from 50 pm to 75 pm, such as from 75 pm to 100 pm.

30. The alloy according to any one of the preceding claims, characterized by comprising an amount of ternary MgZnCa primary precipitates, such as wherein the ternary MgZnCa primary precipitates are Mg6Zn3Ca2.

31. The alloy according to any one of the preceding claims, characterized by comprising less than 10 wt.% of ternary MgZnCa primary precipitates, such as less than 5.0 wt.%, such as less than 4.0 wt.%, such as less than 3.0 wt.%, such as less than 2.0 wt.%, such as less than 1.0 wt.% of ternary MgZnCa primary precipitates.

32. The alloy according to any one of the preceding items, characterized by comprising less than 2.0 wt.% of ternary Mg6Zn3Ca2 primary precipitates, such as less than 1.0 wt.% of ternary MgeZn3Ca2 primary precipitates, said primary precipitates characterized by a diameter size of 20 pm in diameter or less.

33. The alloy according to any one of the preceding claims, wherein the ternary MgZnCa primary precipitates have a size of 5 pm in diameter or less, such as 4 pm, such as 3 pm, such as 2 pm, such as 1.5 pm, such as 1 pm or less.

34. The alloy according to any one of the preceding claims, wherein the ternary MgZnCa primary precipitates have a size of 1 pm or less in diameter.

35. The alloy according to any one of the preceding claims, characterized by comprising an amount of secondary precipitates, such as in the form of prismatic platelets particles.

36. The alloy according to claim 35, wherein the prismatic platelet particles have a size of 50 nm or less in diameter, such as 40 nm, such as 30 nm, such as 25 nm, such as 20 nm, such as 15 nm, such as 10 nm or less in diameter.P6368PC0037. The alloy according to any one of claims 35 to 36, wherein the prismatic platelet particles have a size of approximately 10-30 nm in diameter, more preferably a size of approximately 10-20 nm in diameter.

38. The alloy according to any one of claims 35 to 37, wherein the prismatic platelet particles have a thickness of more than one monolayer, such as at least two atomic layers.

39. The alloy according to any one of claims 35 to 38, wherein the prismatic platelet particles have a thickness of 0.5 nm or more, such as 1 nm or more, such as 1.5 nm or more, such as 2 nm or more.

40. A composition comprising the alloy according to any one of the preceding claims.

41. Use of the alloy according to any one of claims 1 to 39, or the composition according to claim 40, in the manufacture of a medical implant.

42. Use of the alloy according to any one of claims 1 to 39, or the composition according to claim 40, in the manufacture of an orthopaedic biodegradable implant.

43. A biodegradable medical implant comprising the alloy according to any one of claims 1 to 39 or the composition of claim 40.

44. A method for manufacturing a MgZnCaZr quaternary alloy comprising the steps:a. Providing an alloy ingot with an elemental composition according to any one of claims 1 to 9;b. A first heat-treatment comprising heating the ingot to a first temperature (T1) between 200 °C and 500 °C and holding for 2 to 30 hours, such as providing a solid solutioning of all elements capable of forming low- temperature eutectic compositions;c. Optionally, a second heat-treatment subsequent to the first heattreatment, comprising heating the ingot to a second temperature (T2)P6368PC00between 400 °C and 520 °C and holding for 2 to 15 hours, such as providing a solid solutioning of all elements capable of forming high- temperature eutectic compositions; andd. Quenching, such as by immersion in water at room temperature.

45. The method according to claim 44, wherein the first temperature (T1) is between 200 °C and 350 °C.

46. The method according to any one of claims 44 to 45, wherein the first heattreatment is such as to provide a solid solutioning of all elements capable of forming low-temperature eutectic or eutectoid compositions, and wherein the second heat-treatment is such as to provide a solid solutioning of all elements capable of forming high-temperature eutectic or eutectoid compositions.

47. The method according to any one of claims 44 to 46, wherein the quaternary alloy is characterized by a tensile yield strength (TYS) of at least 120 MPa and a structural degradation rate in simulated body fluid of less than 6 mm / year as determined in accordance with ASTM G31-21 , such as is characterized by a tensile yield strength (TYS) of at least 150 MPa and a structural degradation rate in simulated body fluid of less than 3 mm / year as determined in accordance with ASTM G31 -21.

48. The method according to claim 47, wherein the structural degradation rate is determined in accordance with ASTM G31-21 for an alloy sample in a simulated body fluid at 37±0.5 °C and pH 7.4±0.1 , wherein the simulated body fluid comprises Hank’s Balanced Salt Solution, wherein the alloy sample is in the form of a disc of approximately 1 mm in thickness and 10 mm diameter, and wherein the simulated body fluid volume to specimen surface ratio is 0.4244 mL / mm249. The method according to claim 48, wherein the structural degradation rate is determined based on average values of at least four alloy samples, wherein the alloy samples are mechanically ground on both sides using a manual grinding tool, SiC paper and no lubricants down to P4000 grit, and wherein the simulated body fluid comprises Hank’s Balanced Salt Solution modified to contain 1.6 g / LP6368PC00sodium bicarbonate (NaHCOs) and 0.265 g / L calcium chloride dihydrate (CaCI2-2H2O).

50. The method according to any one of claims 44 to 49, wherein the quaternary alloy is characterized by a tensile yield strength (TYS) of 120 MPa to 160 MPa and / or a structural degradation rate in simulated body fluid of less than 6 mm / year.

51. The method according to any one of claims 44 to 50, further comprising at least one of the following steps subsequent to the quenching step d:a. Machining; and / orb. Deformation processing; and / orc. Aging.

52. The method according to any one of claim 51 , wherein the machining step subsequent to step d comprises machining of the heat-treated ingot into a billet.

53. The method according to any one of claims 51 to 52, wherein the deformation processing step subsequent to step d comprises one or more of extrusion, rolling, drawing, or forging.

54. The method according to any one of claims 51 to 53, wherein the deformation processing step subsequent to step d comprises extrusion, such as direct extrusion into rods, wherein the extrusion is performed subject to the following parameters:a. a temperature above ambient, such as above 250 °C, such as between 300 °C to 350 °C, more preferably at 325 °C;b. a ram speed of 0.1 to 1.0 mm / s or more, such as 0.1 mm / s, 0.2 mm / s, 0.3 mm / s, 0.4 mm / s, 0.5 mm / s, 0.6 mm / s, 0.7 mm / s, 0.8 mm / s, 0.9 mm / s, 1.0 mm / s; preferably 0.5 mm / s; andc. extrusion ratio of 1 :10 to 1 :50 or more, such as 1 :10, 1 :15, 1 :20, 1 :25, 1 :30, 1 :35, 1 :40, 1 :45, 1 :50, preferably 1 :25.P6368PC0055. The method according to any one of claims 44 to 52, wherein the method does not comprise an extrusion, or any other deformation processing step as part of the manufacturing method.

56. The method according to any one of claims 51 to 55, wherein the aging step subsequent to step d comprises a third heat-treatment of the alloy at a third temperature (T3) between 100 °C and 200 °C and holding for 10 to 1600 hours such as to obtain an artificially aged alloy, preferably wherein the third heattreatment is performed between 150-180 °C at a holding time of 15-45 hours.

57. The method according to any one of claims 51 to 55, further comprising at least a step of aging subsequent to the quenching step d, further wherein said aging step subsequent to step d comprises a third heat-treatment of the alloy at a third temperature (T3) between ambient and 100 °C and holding for at least 60 hours, such as for at least 1 year, such as to obtain an aged alloy, preferably wherein the third heat-treatment is performed between 60-100 °C at a holding time of 600-1600 hours.

58. The method according to any one of claims 51 to 55 and 57, wherein the aging step subsequent to step d comprises storage at room-temperature or at a temperature between 50-60 °C for at least 1 week, such as 2, 3, 4, 5, 6, 7, 8, 9, or 10 weeks or more.

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