Metallic glasses made of an alloy containing zr-cu-al-ti-nb

Abstract

The invention relates to a metallic glass formed of an alloy comprising the elements: from 45 to 68 at% of Zr, preferably from 48 to 65 at%, and less than 25 at% of Cu, preferably less than 24 at%; and between 9 and 12 at% of AI, preferably from 9 to 11 at%; and from 0.5 to 10 at% of Ti, preferably from 2 to 8 at%; and from 0.1 to 6 at% of Nb, preferably from 0.5 to 4 at%, more preferably from 1.5 to 3 at%; and other elements at most 0.1 wt% each and at most 0.5 wt% in total; and the total sum of the preceding elements being equal to 100 wt% in total; and the sum of Zr + Nb + Ti is between 64 and 69 at%, preferably from 65 to 68 at%. The invention also relates to a metallic glass part and to the method for manufacturing same.

Description

Description Title: ZR-CU-AL-TI-NB ALLOY METALLIC LENSES technical field

[0001] The invention relates to new zirconium-copper-aluminium (Zr-Cu-Al) alloy metallic glasses, more particularly such Zr-Cu-Al alloy metallic glasses comprising niobium, Nb, and exhibiting improved properties, particularly suitable for medical applications. Previous technique

[0002] Amorphous metal alloys (AMs), also known as metallic glasses, exhibit exceptional mechanical properties compared to their traditional crystalline counterparts: high yield strength and hardness, significant elastic deformation capacity, and high resistance to fatigue, corrosion, and abrasion. Long limited by manufacturing processes that resulted in geometries poorly suited to industrialization, AMA parts can now be produced industrially, notably through a process comprising two successive steps: (i) the melting of a set of pure metal ingots defining the composition of the final material, and then (ii) the extremely rapid cooling of the liquid mixture, leading to solidification without crystal formation or, at the very least, with the amorphous phase being predominant compared to the crystalline phase.This process can then make it possible to produce centimeter-sized parts with sub-micrometer geometric details and very high form factors, sometimes even without subsequent machining operations.

[0003] The unique properties of AMAs have naturally sparked great interest in the design of micro-parts subjected to high mechanical stresses. This interest is growing today due to the need to miniaturize systems in many sectors, particularly in the medical and dental fields.

[0004] The health sector has its own specific characteristics, notably the limitation or exclusion of alloying elements that may be toxic. For human use, excellent corrosion resistance and a high compromise of mechanical properties are essential so that the micro-parts are not only strong but also sufficiently deformable to avoid brittle breakage and the risk of alloy residue entering the body. In addition to these specific properties, the alloy must also exhibit excellent formability; therefore, in this case, excellent moldability for the industrial manufacturing of micro-parts.

[0005] Although AMAs are likely to exhibit exceptional properties, they are also complex to manufacture. Indeed, each element composing an AMA interacts with the others, and this interaction varies depending on the concentration of each of these alloying elements.

[0006] Amorphous ZrCuAl alloys, with or without Ti, initially appear to have potentially interesting properties for medical applications. Indeed, zirconium and titanium can give the alloys good corrosion resistance and are also biocompatible. Furthermore, it is known that amorphous alloys can be obtained in the Zr-Cu-Al, Zr-Ni-Al, and Zr-Co-Al systems. However, the use of Co is not suitable for medical applications due to its carcinogenic nature. Moreover, the allergenic nature of Ni and the high viscosity of Zr-Ni-Al alloys mean that they are not, a priori, suitable for such applications, and it is also difficult to manufacture high-quality micro-parts with these alloys.

[0007] As an example, US patent 9,724,450 B2 discloses (Zr,Ti) alloys a (Ni,Cu,Fe)b(Be,Al,Si,B) c and Zr a (Nb, Ti)bCuc Ald for making medical implants. However, this patent only explicitly discloses the Zr47Ti8Ni10Cu7.5Be27.5 and Zr56,2Tii3,8Nb5,oCu6,9Bei2,5 alloys containing beryllium, an element classified as toxic if ingested, causing skin irritation and allergies, fatal if inhaled, carcinogenic and also known for its proven risk of serious effects on organs following repeated or prolonged exposure according to the CLP regulation (EC No. 1272 / 2008).

[0008] US2013 / 0032252 A1 also cites amorphous zirconium-based alloys for biomedical applications, including alloys ZrNbTiCuAI. However, none of the alloys mentioned are specifically characterized in this patent application and the present inventors have found that none of these alloys, taken together, possesses the properties necessary for actual use in the medical field. Technical problem

[0009] Known solutions do not allow for obtaining a ZrCuAl-based metallic glass micropart that simultaneously limits or excludes alloying elements that may be toxic to humans, offers excellent corrosion resistance, and provides a high compromise of mechanical properties so that the microparts are not only strong but also sufficiently deformable, as well as excellent formability.

[0010] Therefore, there is a need for a new ZrCuAI alloy system to solve the problems outlined above. Description of the invention

[0011] A metallic glass made from an alloy comprising the following elements is proposed: Zr: proportion of 45 to 68 atomic percent, preferably 48 to 65 atomic percent, and Cu: proportion less than 25 atomic percent, preferably less than 24 atomic percent; and Al: proportion between 9 and 12 atomic percent, preferably from 9 to 11 atomic percent; and Ti: proportion of 0.5 to 10 atomic percent, preferably 2 to 8 atomic percent; and Note: proportion of 0.1 to 6 atomic %, preferably 0.5 to 4 atomic %, more preferably 1.5 to 3 atomic %; and other elements at most 0.1% by weight each and at most 0.5% by weight in total; and the total sum of the proportions of the aforementioned elements being equal to 100% by total weight; and the sum of the proportions of Zr + Nb + Ti is between 64 and 69 atomic %, preferably from 65 to 68 atomic %.

[0012] According to another aspect, a piece made of metallic glass is proposed, as described previously.

[0013] From another perspective, a manufacturing process for a metallic glass part is also proposed, as described previously and comprising the following steps: - to melt a mixture of metals to obtain an alloy, - mold the resulting alloy in a mold, optionally a mold including a sacrificial insert, - cool the cast alloy at a rate exceeding the critical crystallization rate of the alloy, to obtain an amorphous alloy preform or an amorphous alloy part, - to demold the amorphous alloy preform or the amorphous alloy part, and, optionally, to separate the sacrificial insert from the latter, preferably by chemical dissolution, - Optionally, machine the amorphous alloy preform, preferably by laser machining, turning, bar turning and / or cylindrical grinding or centerless grinding, to obtain an amorphous alloy part with a predetermined geometry, - optionally, perform at least one finishing step of the amorphous alloy part such as a surface texturizing step, a chemical machining step and / or a chemical surface passivation treatment.

[0014] The features described in the following paragraphs may optionally be implemented. They may be implemented independently or in combination with each other.

[0015] According to one provision, the metallic glass according to the invention comprises an amorphous phase fraction greater than 50%, preferably greater than 60%, more preferably greater than 70% and even greater than 80%.

[0016] According to one possibility, the metallic glass according to the invention comprises a crystalline phase fraction strictly less than 50%, preferably strictly less than 40%, more preferably strictly less than 30%, more preferably strictly less than 20%.

[0017] The determination of the amorphous fraction of metallic glass according to the invention will be explained in more detail below in the part describing the embodiments and illustrated in figures 3 to 5.

[0018] According to an advantageous embodiment, the metallic glass is such that: Zr is between 50 and 62 atomic %, preferably from 55 to 60 atomic %, more preferably from 58 to 60 atomic %.

[0019] According to another embodiment, the metallic glass is such that the proportion of Cu is 19 to 24 atomic %, preferably 20 to 24 atomic %, more preferably 21 to 24 atomic % and; more preferably still 22 to 24 atomic %.

[0020] Advantageously, the metallic glass is such that the proportion of Ti is from 3 to 8 atomic%, preferably from 4 to 7 atomic% and, even more preferably, between 5 and 7 atomic%.

[0021] Preferably, the metallic glass is selected from: Zr59Cu23AlioTieNb2, ZreiCu23AlioTi4Nb2, ZreiTi2Nb4Cu23Alio, ZreoTi4Nb2Cu24Alio, Zr61,2Ti4,9Nbl,9CU22,9Al9,1, Zr59Ti4,75NblCU23,5All1.75, Zr6O,9Ti6Nbo,lCU23AllO, Zr59Ti3.5Nbl,75CU24All1.75, Zr58Ti7Nbo.4Cu24.5All 0.1, Zr57Ti4.6Nb2.5CU24All1.9, Zr60.25Ti4.5Nbl,5CU22All1.75, Zr65Til.8Nbo.8Cu23.lAI9, 3, and Zr61 .95^4, 1 Nb2.7Cu22AI9.25.

[0022] According to one embodiment, the metallic glass part has a critical thickness greater than or equal to 2 mm, preferably greater than or equal to 3 mm and, even more preferably greater than or equal to 5 mm.

[0023] The critical thickness is a well-known characteristic of those skilled in the art; it is described in particular in the document "Amorphous Metallic Alloys; Yannick Champion; Techniques de l'ingénieur; Ref.: M4025 V1 and in particular in chapter 2 which deals with the preparation of amorphous metallic materials and in particular the cooling rate and the amorphization capacity of these materials - point 2.1 (pages M 4 025 -7 and following)". This review was published in June 2011 and then revalidated in October 2017, and perfectly reflects the general knowledge of a person skilled in the art. As will be seen later, the critical thickness measurement performed within the framework of the invention uses the measurement method described in the article above.

[0024] According to one possibility, the critical thickness of the metal glass part is determined by successive moldings of plates of the same surface area and different thicknesses, molded from the liquid state under predefined conditions. According to one provision, molding includes melting the alloy, arranging the alloy in a mold followed by cooling the alloy. Depending on other characteristics, the method for determining the critical thickness includes one or more of the following optional characteristics considered alone or in combination: - The surface area of ​​the plates is approximately 2 cm 2 . - The melting temperature of Tl + 150°C with Tl, the liquidus temperature of the alloy (in °C). - The mold is made of CuC1 type copper. - The maximum cooling temperature is approximately twenty degrees Celsius (20°C). - The alloy is developed and molded under an inert and high purity atmosphere (e.g., under argon of quality 6.0) or under secondary vacuum (pressure < 10-4 mbar). - The molding is carried out under a pressure of 20 MPa. - After molding, the plates are cut to obtain a slice, that is to say a longitudinal section of the plate, of different thicknesses. - The resulting slices are analyzed by X-ray diffraction to determine whether they exhibit an amorphous or crystalline structure. The critical thickness is then determined as the maximum thickness for which the structure is "completely amorphous" in the sense that the X-ray diffraction analysis of the alloy does not reveal any crystallinity peaks.

[0025] According to one embodiment, the metallic glass part exhibits a compromise of mechanical properties, evaluated according to a 3-point bending test, such as: - the yield strength, oel, is greater than 1500 MPa, preferably greater than 1525 MPa, and more preferably greater than 1550 MPa; and - the plastic contribution to the deflection, fp, is greater than 2 mm, preferably greater than or equal to 2.1 mm, more preferably greater than or equal to 2.2 mm; and / or - the percentage of tests for which the deflection at break, fr, exceeds a value corresponding to 2 times the thickness of the specimen is greater than or equal to 80%, preferably greater than or equal to 90%, more preferably equal to 100%.

[0026] According to one possibility, the test tube is the metallic glass piece according to the invention.

[0027] According to one provision, the 3-point bending test is carried out in the direction of the thickness of the metallic glass part of the invention.

[0028] According to one possibility, the elastic limit, oel, is calculated by applying the following formula 1: 3 x Fe x L f fe 2 xbx A 2 with L being the length between the supports, for example L = 10 mm, b being the width of the part, for example b = 10 mm, h being the thickness of the part, for example h = 1 mm, Fe being calculated according to the following formula 2: Fe = 2Fmax / 3 with Fmax: the maximum force value recorded at the force plate of the part, and for example the traverse speed v is 0.005 mm / s.

[0029] According to one provision, the plastic contribution to the deflection, fp, of the metallic glass part is calculated according to the following formula 3: fP = f r — f e With fe: the deflection reached at a force level corresponding to Fe, i.e. the force 2Fmax / 3; and fr being the value of the deflection at the break of the part.

[0030] According to another embodiment, the metallic glass part has corrosion resistance, evaluated according to ISO 10271:2020, such that the width of the passivation plate AE is greater than 0.20 V / ECS, preferably greater than or equal to 0.30 V / ECS, more preferably greater than 0.45 V / ECS.

[0031] The corrosion resistance of the samples is evaluated according to the protocol defined in the ISO 10271:2020 standard for oral and dental medicine.

[0032] According to one possibility, the corrosion resistance of the metallic glass part samples is measured according to the following steps: - preparation of samples, - placement of samples in a corrosive environment, - measure the EOCP free potential of the sample over a predetermined period, - to plot a current-potential curve at a predetermined rate from a predetermined potential until the current reaches several tens of times the value of the puncture current, - detection of bites, and - determination of the Ecor corrosion potential.

[0033] According to one provision, the width of the passivation plateau AE is calculated as follows: AE=Epiq-Ecor; with Epiq the first prick potential.

[0034] One possibility is that sample preparation includes a polishing step until a "mirror polished" surface is obtained.

[0035] For example, the samples are polished using SiC paper and then a diamond suspension to a particle size of 1 pm, resulting in a "mirror polished" surface.

[0036] According to one possibility, sample preparation also includes, after the polishing step, a degreasing step of the samples, for example with acetone, and then optionally a cleaning step, for example with ultrasound using ethanol, and then with distilled water.

[0037] According to one arrangement, the corrosive medium in which the samples are placed is obtained by preparing a 9g / L NaCl solution at pH 7.4±0.1 buffered with a 4% NaOH solution and a 1% lactic acid solution.

[0038] In one possibility, the corrosion test is carried out at a temperature of 37°C±1°C.

[0039] According to one possibility, the said solution is deaerated by argon bubbling for a duration of at least 30 minutes before the samples are disposed of.

[0040] According to one provision, a low level of bubbling is maintained during the test.

[0041] The measurement time of the EOCP free potential of the sample is approximately 2 hours.

[0042] The current-potential curve is performed at a rate of +1 mV / s from Eocp-150mV until the current reaches 100 times the value of the sting current.

[0043] Depending on one possibility, the samples are then rinsed, dried and again observed under an optical microscope to detect pitting.

[0044] According to one provision, the Ecor corrosion potential is determined by the potential value for which the current is zero on the current-potential curve.

[0045] Advantageously, the metal-glass part is chosen from: all or part of a surgical or microsurgical instrument, all or part of a dental instrument, all or part of a suture device, all or part of an implant, in particular a dental, acoustic or orthopedic implant. Brief description of the drawings

[0046] Other features, details, and advantages of the invention will become apparent upon reading the detailed description below and analyzing the accompanying drawings, in which:

[0047] Figure 1 represents a 3-point bending curve, obtained during mechanical tests, allowing evaluation of the elastic limit, oel, the deflection at break, fr, and the plastic contribution to the deflection, fp, of the amorphous metallic alloy samples.

[0048] Figure 2 represents a polarization curve obtained according to the corrosion test described in ISO 10271:2020 and allowing in particular to evaluate the width of the AE passivation plateau of the amorphous metallic alloy samples.

[0049] Figure 3 represents an XRD analysis of an amorphous metallic alloy.

[0050] Figure 4 represents an XRD analysis of a partially amorphous metallic alloy.

[0051] Figure 5 represents an XRD analysis of a crystalline metallic alloy. Description of the implementation methods

[0052] The drawings and description below contain, for the most part, elements of a definite nature. They can therefore not only serve to better explain the present invention but also contribute to its definition, if necessary.

[0053] In the above, it is necessary to clarify the following definitions.

[0054] Here, "metallic glass," "amorphous metallic alloy," or "AMA" refers to metals or metallic alloys that are not crystalline, meaning their atomic distribution is predominantly random. However, it is difficult to obtain a 100% amorphous metallic alloy because a fraction of the material usually remains crystalline. Therefore, this definition can be generalized to metals or metallic alloys that are partially crystalline and thus contain a fraction of crystals, as long as the amorphous fraction is larger than the crystalline fraction. Glasses metallic according to the present invention have an amorphous phase fraction greater than 50%, preferably greater than 60%, more preferably greater than 70% and even greater than 80%.

[0055] It is specified here that a metallurgical structure is said to be "totally amorphous" within the meaning of the present invention when an X-ray diffraction analysis as described below does not reveal any crystallization peaks. A metallurgical structure is said to be "partially amorphous" within the meaning of the present invention when an X-ray diffraction analysis as described below reveals some crystallization peaks. Unless otherwise specified, the term "amorphous" is used for both alloys described as "totally amorphous" and for alloys described as "partially amorphous" within the meaning of the invention. Such an evaluation of the amorphous nature of a metallic alloy is detailed in the article Cheung et al., 2007 (Cheung et al. (2007) "Thermal and mechanical properties of Cu-Zr-Al bulk metallic glasses" doi:10.1016 / j.jallcom.2006.08.109).It allows for an average analysis over a surface and eliminates the few inevitable metallurgical defects, while analyzing only crystals of significant size, i.e., larger than a few nanometers and / or present in significant quantity. Figures 3, 4, and 5 represent an XRD analysis as described previously. These figures show the intensity of the diffracted beam as a function of the angle between the incident and diffracted beams. Figure 3 is an XRD analysis of a metallic alloy in a "completely amorphous" state, where the amorphous fraction is far more abundant than the crystalline fraction. Figure 4 is a similar analysis performed on an alloy in a "partially amorphous" state, where the amorphous fraction is more abundant than the crystalline fraction. In this figure, the characteristic hump of amorphous structures is visible, but also with the presence of peaks.Figure 5 shows a similar analysis performed on a crystalline alloy, where the crystalline fraction is predominant compared to the amorphous fraction. In this figure, the characteristic hump of AMAs is not present, and the crystallinity peaks are clearly visible.

[0056] The "critical thickness" (denoted ec) of a specific amorphous metallic alloy is defined as the maximum limiting thickness below which the alloy The metallic alloy exhibits a "totally amorphous" metallurgical structure, or a thickness beyond which it is no longer possible to obtain a "totally amorphous" metallurgical structure, when the metallic alloy is cast from a liquid state and subjected to rapid cooling such that heat transfer within the metallic alloy is optimal. More specifically, the critical thickness is determined by successive castings of plates approximately 2 cm thick. 2and of varying thicknesses, molded from the liquid state under the following conditions: - The alloy is melted at a temperature of Tl + 150°C with Tl, the liquidus temperature of the alloy (in °C); - The alloy is cast in a CuC1 type copper mold and is cooled to a maximum temperature of about twenty degrees Celsius (20°C). The alloy is prepared and molded under an inert, high-purity atmosphere (e.g., argon of grade 6.0) or under secondary vacuum (pressure < 10⁻⁴ mbar). The alloy is molded using a system that applies a differential pressure to facilitate molding and ensure close contact between the alloy and the mold walls, thus ensuring rapid cooling. The molding process can be carried out under a pressure of 20 MPa. This overpressure application system can be mechanical (piston) or gaseous. - After molding, the plates are cut to obtain a slice, that is to say a longitudinal section of the plate, of different thicknesses. - The resulting slices are analyzed by X-ray diffraction to determine whether they exhibit an amorphous or crystalline structure. The critical thickness is then determined as the maximum thickness for which the structure is "completely amorphous" in the sense that the X-ray diffraction analysis of the alloy does not reveal any crystallinity peaks.

[0057] According to the present description, the elastic limit, oel, and the plastic contribution to the deflection, fp, are evaluated as follows. The mechanical tests are carried out on a DY34 mechanical testing machine (Adamel Lhomargy). These are 3-point bending tests in the direction of the thickness of the sample. The test parameters are as follows: - Length between supports L=10 mm - Sample width b=10 mm - Sample thickness h=1 mm - Sample length 1 = 15 mm - Traverse velocity v=0.005 mm / s The 3-point bending curve has a first linear elastic part, during which the sample deforms elastically, then a plastic plateau, during which the deformation is plastic (see figure 1). The elastic limit, oel, is calculated according to the following formula 1: 3 x Fe x L f fe 2 xbx A 2 where Fe is calculated according to the following formula 2: Fe = 2Fmaxf3 with Fmax: the maximum force value recorded at the force plateau. The plastic contribution to the deflection, fp, is calculated according to the following formula 3: fP = fr - fe with fe is the deflection reached at a force level corresponding to Fe, i.e., the force 2Fmax / 3; and - fr is the break arrow.

[0058] The test is stopped when the specimen breaks or the deflection reaches a value of 2.5 mm. The number of tests for which the deflection at break, fr, exceeds a value corresponding to 2 times the thickness of the specimen (fr > 2*h) is counted. Alloys for which the percentage of tests where the deflection at break, fr, exceeds a value corresponding to 2 times the thickness of the specimen (fr > 2*h) is high and, more particularly, equal to 100%, exhibit remarkable and reproducible plasticity, which is essential for the applications in question. Figure 1 illustrates a 3-point bending curve obtained according to the test described above.

[0059] Each alloy has its own specific crystallization temperature (Tx) and glass transition temperature (Tg). These temperatures are measured using a dual-scanning calorimeter (DSC) at a rise rate of 20°C / min. The Tg and Tx temperatures are then extracted from the DSC curves.

[0060] For each alloy, it is therefore possible to determine the difference ATx between the crystallization temperature Tx and the glass transition temperature Tg, i.e. ATx=Tx-Tg.

[0061] According to this description, corrosion resistance is evaluated as follows: samples are polished using SiC paper and then a diamond suspension to a particle size of 1 µm, resulting in a mirror-polished surface. They are then observed under an optical microscope. Just before the corrosion test, the samples are degreased with acetone and then cleaned ultrasonically with ethanol, followed by distilled water. In accordance with ISO 10271:2020, the corrosion test is carried out in a 9 g / L NaCl solution at pH 7.4 ± 0.1, buffered with 4% NaOH and 1% lactic acid solutions, at a temperature of 37°C ± 1°C. The solution is deaerated by argon bubbling for at least 30 minutes. Low bubbling is maintained throughout the test.The corrosion test consists of measuring the free potential (EOCP) of the sample for 2 hours, then plotting a current-potential curve at a rate of +1 mV / s from Eocp - 150 mV until the current reaches 100 times the pitting current. The samples are then rinsed, dried, and observed again under an optical microscope to detect pitting. The corrosion potential (Ecor) is the potential value at which the current is zero on the current-potential curve. The passivation plate width (AE) is calculated as follows: AE = E. P iq-Ecor; with E P iq the potential for the first sting. Figure 2 illustrates a polarization curve obtained according to the corrosion test described above.

[0062] As previously stated, the AMAs known until now, particularly those whose major elements are zirconium, copper and aluminum, exhibit low corrosion resistance and / or a compromise of mechanical properties, particularly for properties such as their elastic limit and their plastic contribution to the deflection, which is not optimized and / or lower processability making their industrialization complex.

[0063] Against all expectations, the present inventors were able to remedy these problems and reference is now made to the amorphous metallic alloy, also referred to as "metallic glass", which is the subject of the present invention.

[0064] This metallic glass is thus formed from an alloy comprising: Zr: from 45 to 68 atomic percent, preferably from 48 to 65 atomic percent; and Cu: less than 25 atomic percent, preferably less than 24 atomic percent; and Al: between 9 and 12 atomic percent, preferably from 9 to 11 atomic percent; and Ti: from 0.5 to 10 atomic percent, preferably from 2 to 8 atomic percent; and Nb: from 0.1 to 6 atomic %, preferably from 0.5 to 4 atomic %, more preferably from 1.5 to 3 atomic %; and other elements at most 0.1% by weight each and at most 0.5% by weight in total; and the total sum of the said preceding elements being equal to 100% by weight in total; and the sum Zr + Nb + Ti is between 64 and 69 atomic %, preferably from 65 to 68 atomic %.

[0065] Metallic glass is formed from an alloy containing zirconium, Zr. More specifically, it comprises 45 to 68 atomic percent of Zr, preferably 48 to 65 atomic percent, more preferably between 50 and 62 atomic percent, and even more preferably between 55 and 60 atomic percent, or even between 58 and 60 atomic percent. The Zr content of the alloy notably influences The critical thickness, ec, of the alloy. More generally, the content of each alloying element must be specifically selected to obtain a metallic glass with good vitrification capacity. Indeed, it is the overall formulation of the alloy that determines its critical thickness.

[0066] Metallic glass is formed from an alloy that also includes copper, Cu. More specifically, it contains less than 25 atomic percent, preferably less than 24 atomic percent, of Cu. Advantageously, the Cu content is such that it is 19 to 24 atomic percent, preferably 20 to 24 atomic percent, more preferably 21 to 24 atomic percent, and even more preferably 22 to 24 atomic percent. The Cu content of the alloy influences, in particular, the critical thickness, ec, and the corrosion resistance of the alloy. Furthermore, Cu can be cytotoxic when present in large quantities. It is therefore essential for the intended applications to limit its content in the alloy.

[0067] Metallic glass is formed from an alloy that also contains titanium (Ti). The Ti content is such that: Ti ranges from 0.5 to 10 atomic percent, preferably from 2 to 8 atomic percent, more preferably from 3 to 8 atomic percent, even more preferably from 4 to 7 atomic percent, or between 5 and 7 atomic percent. The Ti content of the alloy notably influences the critical thickness (ec) of the alloy.

[0068] Metallic glass is formed from an alloy that also contains aluminum, Al. The Al content is such that it is between 9 and 12 atomic percent, preferably between 9 and 11 atomic percent. Contrary to expectations, it has been shown that such an Al content makes it possible to obtain a metallic glass with an excellent compromise between mechanical properties, even though the yield strength (oel) and the plastic contribution to deflection (fp) are properties known to be contradictory. Furthermore, this selected Al content makes it possible to obtain a metallic glass with excellent and highly reproducible plasticity; this is reflected in specimens that can withstand a deflection greater than twice the thickness of the specimen (fr > 2h).

[0069] Metallic glass is formed from an alloy that also contains niobium, Nb. The Nb content is such that: Nb from 0.1 to 6 atomic %, preferably from 0.5 to 4 atomic %, more preferably from 1.5 to 3% atomic. Contrary to expectations in this Zr-Cu-Al alloy system including Ti and Nb, it has been shown that such a selected Nb content makes it possible in particular to improve the corrosion resistance of the metallic glass, in particular its passivity, AE.

[0070] Metallic glass is formed from an alloy that may also include other elements, also called "residual impurities," such as oxygen, carbon, phosphorus, and / or other metallic elements not mentioned above. These residual impurities may also be any other element(s) not intentionally added during the mixing of metals to obtain the alloy blank. The impurity content of the alloy, expressed as a percentage by weight, is at most 0.1 for each impurity and at most 0.5 for the total. More preferably, this content is, expressed as a percentage by weight, at most 0.05 for each impurity and at most 0.2 for the total. Preferably, the alloy comprises less than 250 ppm (parts per million) by weight, more preferably less than 200 ppm by weight, and even more preferably less than 150 ppm by weight of each of these impurities.

[0071] The metallic glass alloy also includes a selected content of Zr, Nb, and Ti such that the sum of Zr + Nb + Ti is between 64 and 69 atomic percent, preferably between 65 and 68 atomic percent. This selection of Zr, Nb, and Ti contents makes it possible to obtain a metallic glass with excellent corrosion resistance and very good vitrification capacity, evidenced in particular by a high critical thickness, ec.

[0072] According to a preferred embodiment, the amorphous metallic alloy is selected from: Zr59Cu23AlioTieNb2, ZreiCu23AlioTi4Nb2, ZreiTi2Nb4Cu23Alio, Zr60Ti4Nb2CU24All0, Zr61,2Ti4,9Nbl,9CU22,9Al9,1, Zr59Ti4,75NblCU23,5All1.75, Zr6O,9Ti6Nbo,l CU23AllO, Zr59Ti3,5Nbl,75CU24Aln,75, Zr58Ti7Nbo.4Cu24.5All 0,1, Zr57Ti4,6Nb2.5CU24All1.9, Zr60.25Ti4,5Nbl,5CU22All1.75, Zr65Til .8Nbo.8Cu23.lAI9, 3, and Zrei ,9sTi4,i Nb2.7Cu22AI9.25.

[0073] The alloy as described above makes it possible, against all expectations, to obtain metallic glass parts exhibiting a truly exceptional compromise of properties as indicated above.

[0074] According to a preferred embodiment, the metallic glass part has a critical thickness greater than or equal to 2 mm, preferably greater than or equal to 3 mm and, even more preferably greater than or equal to 5 mm.

[0075] The metallic glass part may also exhibit a compromise in mechanical properties, evaluated according to a 3-point bending test, such as: - the yield strength, o el, is greater than 1500 MPa, preferably greater than 1525 MPa, more preferably greater than 1550 MPa, and even more preferably greater than 1565 MPa; and - the plastic contribution to the deflection, fp, is greater than 2 mm, preferably greater than or equal to 2.1 mm, more preferably greater than or equal to 2.2 mm; and / or - the percentage of tests for which the deflection at break, fr, exceeds a value corresponding to 2 times the thickness of the specimen is greater than or equal to 80%, preferably greater than or equal to 90%, more preferably equal to 100%.

[0076] The metallic glass part is also likely to exhibit corrosion resistance, evaluated according to ISO 10271:2020, such that the width of the AE passivation plate is greater than 0.20 V / ECS, preferably greater than or equal to 0.30 V / ECS, more preferably greater than 0.45 V / ECS, and more preferably greater than or equal to 0.50 V / ECS.

[0077] Such a piece made of metallic glass can be obtained, in particular, using the following manufacturing process: - to melt a mixture of metals to obtain an alloy, - mold the resulting alloy in a mold, optionally a mold including a sacrificial insert, - cool the cast alloy at a rate exceeding the critical crystallization rate of the alloy, to obtain an amorphous alloy preform or an amorphous alloy part, - demold the amorphous alloy preform or the amorphous alloy part, and, optionally, separate the sacrificial insert from the latter, preferably by chemical dissolution - Optionally, machine the amorphous alloy preform, preferably by laser machining, turning, bar turning and / or cylindrical grinding or centerless grinding, to obtain an amorphous alloy part with a predetermined geometry, - optionally, perform at least one finishing step of the amorphous alloy part such as a surface texturizing step, a chemical machining step and / or a chemical surface passivation treatment.

[0078] Preferably, the steps described above are carried out successively in the order described.

[0079] Advantageously, the molten metal alloy can be shaped to obtain a billet. The billet is then melted, molded, and cooled to obtain an amorphous alloy preform or an amorphous alloy part.

[0080] Advantageously, the alloy is cast in a mold incorporating a sacrificial insert. Such a mold is described, in particular, in application WO 2020 / 128170 A1. This insert may consist of a silicon sacrificial insert that is subsequently dissolved by selective chemical dissolution. Optionally, it may be necessary to perform a step to remove excess material from the amorphous alloy preform or the amorphous alloy part, for example, by machining.

[0081] Optionally, the amorphous alloy preform or the amorphous alloy part is machined, preferably by laser machining, turning, bar turning and / or cylindrical grinding or centerless grinding, to obtain an amorphous alloy part according to a predetermined geometry.

[0082] Optionally, at least one finishing step can be performed on the amorphous alloy part, such as a surface texturing step, a chemical machining step, and / or a chemical surface passivation treatment. The surface texturing step is preferably performed using a laser. Advantageously, the chemical machining step is performed by electropolishing. In a preferred embodiment, the chemical passivation treatment of The surface is treated by chemical attack with HNO3 to further increase the corrosion resistance of the finished part. Industrial application

[0083] The invention may find applications particularly in the medical or dental fields.

[0084] The metal-glass parts according to the invention are particularly suitable for the manufacture of all or part of a surgical or microsurgical instrument, all or part of a dental instrument, all or part of a suture device, all or part of an implant, in particular a dental, acoustic or orthopedic implant.

[0085] The invention is not limited to the above description and / or to examples 1 and 2 described below, but encompasses all variants that a person skilled in the art may consider within the framework of the protection sought. Examples Example 1

[0086] Seven different compositions of metallic glass alloys, detailed in Table 1, were studied.

[0087] The primary alloys were produced by arc melting (T>2500°C) of high-purity (>99.9%) bulk fragments of base elements under an argon atmosphere, using a Ti getter to detect any trace of harmful contamination. Each primary alloy was melted at least five times to ensure high chemical homogeneity. The alloy was injected into a mold to obtain a 1 mm thick plate sample. This thickness, less than the critical thickness, ensures that the resulting structure is amorphous. For all samples, the amorphous fraction is predominant compared to the crystalline fraction.

[0088] Corrosion resistance was evaluated according to the test described above in this description. The passivity (AE) of each alloy is reported in Table 1.

[0089] Table 1

[0090] The alloy Zr6iCu2sAli2Ti2, (input 1) free of Nb, exhibits poor corrosion resistance (Zr6iCu2sAli2Ti2: AE «0.30 V).

[0091] Adding Nb to the ZrCuAITi alloy system (entries 2 to 7) improves the corrosion resistance of AMA in a corrosive environment. Example 2

[0092] Six different compositions of metallic glass alloys, detailed in Table 2, were studied.

[0093] The alloys were obtained according to the protocol described in example 1. For all samples, the amorphous fraction is predominant compared to the crystalline fraction.

[0094] The yield strength (θel), the plastic contribution to deflection (θp), and the percentage of tests for which the deflection at failure (θfr) exceeded a value corresponding to twice the specimen thickness were evaluated using three-point bending tests, as described earlier in this document. At least three tests were performed for each composition to ensure good reproducibility of the results. The results are presented in Table 2.

[0095] Table 2

[0096] The alloy Zr62.2Cu23.5Al7.5Ti5.4Nbi.4 (entry 1) exhibits a yield strength, ael, that is too low for the intended application (oel < 1500 MPa). The alloys Zr57.4Cu23Al14Ti3.8Nb1.9, Zr59.7Cu25Al14Ti2Nbi.3, and ZreiCu2oAl14Ti4Nb2 (entries 2 to 4) exhibit a plastic contribution to deflection, fp, that is too low for the intended applications (fp < 2.00 mm), and the number of specimens that withstand a deflection greater than twice the specimen thickness (fr > 2*h) is less than or equal to 67% for these alloys, indicating both insufficient plasticity and reproducibility for the intended application.

[0097] The ZreiCu23AlioTi4Nb2 and Zr59Cu23AlioTieNb2 alloys (entries 5 and 6) are the only ones to present an excellent compromise of mechanical properties; the elastic limit, oel, and the plastic contribution to deflection, fp, are properties known to be contradictory. Example 3

[0098] Eleven different compositions of metallic glass alloys, detailed in Table 3, were studied.

[0099] The alloys were obtained according to the protocol described in example 1. For all samples, the amorphous fraction is predominant compared to the crystalline fraction.

[0100] The yield strength (oel), the plastic contribution to deflection (fp), and the percentage of tests for which the deflection at failure (fr) exceeded a value corresponding to twice the specimen thickness were evaluated using three-point bending tests, as described above. At least three tests were performed for each composition to ensure good reproducibility of the results. The results are presented in Table 3.

[0101] Table 3 These eleven alloys all present an excellent compromise of mechanical properties: a high yield strength, high plasticity and good reproducibility.

Claims

Demands 1. Metallic glass formed from an alloy comprising the elements: Zr: from 45 to 68 atomic percent, preferably from 48 to 65 atomic percent, and Cu: less than 25 atomic percent, preferably less than 24 atomic percent; and Al: between 9 and 12 atomic percent, preferably from 9 to 11 atomic percent; and Ti: from 0.5 to 10 atomic percent, preferably from 2 to 8 atomic percent; and Nb: from 0.1 to 6 atomic %, preferably from 0.5 to 4 atomic %, more preferably from 1.5 to 3 atomic %; and other elements at most 0.1% by weight each and at most 0.5% by weight in total; and the total sum of the said preceding elements being equal to 100% by weight in total; and the sum Zr + Nb + Ti is between 64 and 69 atomic %, preferably from 65 to 68 atomic %.

2. Metallic glass according to claim 1 wherein Zr is between 50 and 62 atomic %, preferably from 55 to 60 atomic %, more preferably from 58 to 60 atomic %.

3. Metallic glass according to any one of the preceding claims such as Cu of 19 to 24 atomic %, preferably of 20 to 24 atomic %, more preferably of 21 to 24 atomic % and; more preferably still of 22 to 24 atomic %.

4. Metallic glass according to any one of the preceding claims such as Ti of 3 to 8 atomic percent, preferably of 4 to 7 atomic percent and, more preferably still, between 5 and 7 atomic percent.

5. Metallic glass according to any one of the preceding claims selected from: Zr59Cu23AlioTieNb2, ZreiCu23AlioTi4Nb2, ZreiTi2Nb4Cu23Alio, Zr60Ti4Nb2CU24All 0, Zr61 ,2Ti4,9Nbl ,9CU22,9Al9,1 , Zr59Ti4,75Nbl CU23,5All1.75, Zreo.gTieNbo C123AI10, Zr59Ti3,5Nbi,75Ci 24Alii,75, Zr58Ti7Nbo,4Cu24,5Alio,i, Zr57Ti4,6Nb2.5CU24All1,9, Zr60,25Ti4,5Nbl,5CU22All1,75, Zr65Til,8Nbo,8CU23,lAl9.3, and ZC61,95Ti4,1Nb2.7Cu22AI9.

25.

6. Metallic glass according to any one of the preceding claims, comprising an amorphous phase fraction greater than or equal to 50%, preferably greater than or equal to 60%, more preferably greater than or equal to 70% and even greater than or equal to 80%.

7. Metallic glass part in which the metallic glass is according to any one of the preceding claims, the metallic glass part having a critical thickness greater than or equal to 2 mm, preferably greater than or equal to 3 mm and, even more preferably greater than or equal to 5 mm.

8. Metallic glass part according to claim 7 wherein the critical thickness of the metallic glass part is determined by successive moldings of plates of the same surface and of different thicknesses, molded from the liquid state under predefined conditions.

9. Metallic glass part according to any one of claims 7 or 8, exhibiting a compromise of mechanical properties, evaluated according to a 3-point bending test, such as: - the yield strength, oel, is greater than 1500 MPa, preferably greater than 1525 MPa, and more preferably greater than 1550 MPa; and - the plastic contribution to the deflection, fp, is greater than 2 mm, preferably greater than or equal to 2.1 mm, more preferably greater than or equal to 2.2 mm; and / or - the percentage of tests for which the deflection at break, fr, exceeds a value corresponding to 2 times the thickness of the specimen is greater than or equal to 80%, preferably greater than or equal to 90%, more preferably equal to 100%.

10. Metallic glass part according to claim 9 in which the yield strength, oel, is calculated by applying the following formula 1: with L being the length between the supports, for example L = 10 mm, b being the width of the part, for example b = 10 mm, h being the thickness of the part, for example h = 1 mm, Fe being calculated according to the following formula 2: Fe = 2Fmax 3 with Fmax: the maximum force value recorded at the force plate of the part, and for example the traverse speed v is 0.005 mm / s.

11. Metallic glass part according to any one of claims 9 or 10, wherein the plastic contribution to the deflection, fp, of the metallic glass part is calculated according to the following formula 3: fp = fr - fe with fe: the deflection reached at a force level corresponding to Fe, i.e. the force 2Fmax / 3; and fr being the value of the deflection at the break of the part.

12. Metallic glass part according to any one of claims 7 to 11, having corrosion resistance evaluated according to ISO 10271:2020, wherein the width of the passivation plate AE is greater than 0.20 V / ECS, preferably greater than or equal to 0.30 V / ECS, more preferably greater than 0.45 V / ECS, the width of the passivation plate AE being calculated as follows: AE=E P iq-Ecor; with E P iq represents the potential for first pitting and Ecor the potential for corrosion.

13. Metallic glass part according to claim 12, wherein the corrosion resistance of the metallic glass part samples is evaluated according to the steps of: - preparation of samples, - placement of samples in a corrosive environment, - measure the EOCP free potential of the sample over a predetermined period, - to plot a current-potential curve at a predetermined rate from a predetermined potential until the current reaches several tens of times the value of the puncture current, - detection of bites, and - determination of the Ecor corrosion potential.

14. Metallic glass part according to any one of claims 7 to 13 selected from: all or part of a surgical or microsurgical instrument, all or part of a dental instrument, all or part of a suture device, all or part of an implant, in particular a dental, acoustic or orthopedic implant.

15. A method for manufacturing a metallic glass part according to any one of claims 7 to 14 comprising the following steps: - to melt a mixture of metals to obtain an alloy, - mold the resulting alloy in a mold, optionally a mold including a sacrificial insert, - cool the cast alloy at a rate exceeding the critical crystallization rate of the alloy, to obtain an amorphous alloy preform or an amorphous alloy part, - to demold the amorphous alloy preform or the amorphous alloy part, and, optionally, to separate the sacrificial insert from the latter, preferably by chemical dissolution, - Optionally, machine the amorphous alloy preform, preferably by laser machining, turning, bar turning and / or cylindrical grinding or centerless grinding, to obtain an amorphous alloy part with a predetermined geometry, - optionally, perform at least one finishing step of the amorphous alloy part such as a surface texturizing step, a chemical machining step and / or a chemical surface passivation treatment.

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