Magnesium-rare earth alloy wire for additive manufacturing with high structural stability and method for manufacturing the same

Abstract

This invention discloses a magnesium rare earth alloy wire with high microstructure stability for additive manufacturing and its preparation method. The wire, by mass percentage, comprises: rare earth element (RE): 10.0-15.0%, aluminum (Al): 0.5-5.0%, manganese (Mn): 0.2-2.0%, with the balance being magnesium (Mg). The wire is obtained through melting, extrusion, drawing, and surface treatment processes. On one hand, this invention effectively improves the ductility and toughness of magnesium rare earth alloys, enhancing the plastic deformation capacity of magnesium rare earth alloy ingots during wire making, enabling the production of continuous, fine-diameter additive manufacturing wires. On the other hand, when the wire prepared by this invention is used for additive manufacturing, the resulting magnesium rare earth alloy contains high-density, fine-sized, and thermally stable Al2RE particles, effectively improving the microstructure stability of the additive-manufactured magnesium rare earth alloy and suppressing grain coarsening during subsequent heat treatment and high-temperature service environments.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy technology, and relates to a magnesium rare earth alloy wire with high structural stability for additive manufacturing. Specifically, it relates to a magnesium rare earth alloy wire with high structural stability for additive manufacturing and its preparation method. Background Technology

[0002] Magnesium alloys are the lightest metallic structural materials used in practical applications, possessing high specific strength and stiffness, and excellent casting process performance, making them promising for applications in the meticulously crafted aerospace field. Adding rare earth elements can form rare earth reinforcing phases in magnesium alloys, further improving their absolute strength and heat resistance. Therefore, cast magnesium rare earth alloys have been widely used in the forming of important components such as casings and cabins. With the continuous development of aerospace equipment, the shapes of related components have become more complex, often featuring special structures such as thin walls, complex internal cavities, and irregular curved surfaces. Therefore, it is difficult to meet the relevant technical requirements when forming these complex components using traditional casting or deformation processes.

[0003] Additive manufacturing technology is based on digital models and uses electric arcs, lasers, or plasmas as heat sources to melt and deposit materials layer by layer to create solid objects. It features advantages such as no need for molds, high deposition efficiency, great manufacturing flexibility, and high material utilization. Additive manufacturing can optimize component structures, reduce the number of parts, and enable the integrated manufacturing of large and complex magnesium rare earth alloy components, which is of practical significance for promoting the application of magnesium rare earth alloys in large and complex aerospace components.

[0004] However, additive manufacturing of magnesium rare earth alloys faces two technical bottlenecks: First, the poor plasticity and high deformation resistance of magnesium rare earth alloys make it difficult to prepare the continuous, fine-diameter wires required for additive manufacturing, severely affecting the process continuity and deposition efficiency. Second, the fine grains, large grain boundary volume fraction, and severe residual stress in additively manufactured magnesium rare earth alloys result in poor alloy microstructure stability: grain boundary migration easily occurs at high temperatures, and in severe cases, the grains can coarsen by tens of times, leading to performance deterioration. Therefore, improving the plastic deformation capacity of magnesium rare earth alloys during wire preparation and enhancing the microstructure stability of additively manufactured alloys are critical issues that urgently need to be addressed in this field.

[0005] To address the aforementioned issues, relevant research has been conducted within the industry. Patents CN202210415287.9, CN202210415289.8, and CN202210426813.1 all disclose methods for preparing Mg-Gd-Y-Zn-Zr magnesium rare earth alloy wires suitable for arc-fused-wire additive manufacturing. The prepared magnesium rare earth alloy wires are of uniform diameter, slender, and have a good microstructure and surface quality; however, their microstructure stability has not yet been reported. Patent CN202210276746.X discloses a method for preparing magnesium alloy wires for arc-fused-wire additive manufacturing, reporting that La alloying and high-energy pulse treatment improve the deformability of magnesium rare earth alloys. However, the sample size for each high-energy pulse treatment is limited, and its engineering applicability is still unclear. In our previous publication, we disclosed a method for preparing and using magnesium rare earth alloy welding wire (CN202110413718.3). This patent involves adding zinc, copper, or nickel to the magnesium rare earth alloy to form a long-period ordered structure (LPSO) phase with high thermal stability. The LPSO phase can pin grain boundaries to inhibit grain boundary migration and improve the microstructure stability of the alloy. However, the size of the lamellar LPSO phase within the grains often reaches tens of micrometers, weakening the strengthening effect of the alloy. Patent CN202211065947.1 discloses a controllable dissolution magnesium alloy wire and its preparation method, mainly aimed at improving the solubility of magnesium alloys, thereby enabling applications in shale oil and gas extraction, downhole construction, underground construction, and subsea construction. However, the alloy wire developed in this patent is used directly in its wire state and does not involve subsequent additive manufacturing. Furthermore, this patent does not conduct research on the microstructure stability of additively manufactured components deposited using this alloy. Therefore, the above methods cannot adequately address both the plastic deformation capacity and microstructure stability of additively manufactured magnesium rare earth alloys.

[0006] In summary, the inventors believe that to address the issues of weak plastic deformation capacity and poor microstructural stability in additively manufactured magnesium rare earth alloys, it is essential to develop a magnesium rare earth alloy wire specifically designed for additive manufacturing. On one hand, this involves improving the plastic deformation capacity of magnesium rare earth alloys during extrusion and drawing processes by activating non-basal slip in the α-Mg matrix and increasing the number of effective slip systems. On the other hand, it involves introducing highly stable granular phases to pin grain boundaries, thus ensuring the microstructural stability of the alloy after additive manufacturing. Developing such a magnesium rare earth alloy wire is of significant practical importance for promoting the further application of magnesium rare earth alloys in large and complex aerospace components. Summary of the Invention

[0007] To address the aforementioned shortcomings of existing technologies, this invention provides a magnesium rare earth alloy wire for additive manufacturing with high structural stability and its preparation method. It organically combines a novel alloy formulation and wire preparation process, which not only improves the plastic deformation capability of the magnesium rare earth alloy wire during wire making processes such as extrusion and drawing, but also significantly enhances the structural stability of magnesium rare earth alloy components formed through additive manufacturing.

[0008] To achieve the aforementioned technical effects, this invention proposes a novel composition formula and preparation method for magnesium rare earth alloy wire. This method promotes the formation of a large number of Al2RE particles in the alloy through Al alloying. On one hand, Al2RE particles can act as heterogeneous nucleation sites for α-Mg and refine the grains, thereby improving the alloy's ductility and toughness and enhancing its plastic deformation capacity during wire making. On the other hand, Al2RE particles can effectively pin grain boundaries, inhibit grain boundary migration, and improve the microstructure stability of the additively formed alloy. Simultaneously, Mn alloying significantly reduces the difference in critical shear stress between basal and non-basal slip in the α-Mg matrix, activating non-basal slip in the α-Mg matrix, increasing the number of effective slip systems in the α-Mg matrix, and improving the alloy's plastic deformation capacity. Furthermore, Mn tends to segregate at the interface between Al2RE and the α-Mg matrix, which is beneficial for improving the bonding strength of the phase interface and inhibiting the initiation and propagation of microcracks at the interface. Therefore, the effects of Al alloying and Mn alloying are complementary and indispensable.

[0009] Furthermore, by optimizing the Al and RE content ratio and controlling the cooling rate and applied energy field during casting, the content of particulate Al2RE can be increased while the content of rod-shaped eutectic Al2RE can be reduced. Subsequent extrusion and drawing processes are then used to break up the Al2RE particles in the wire, increasing the Al2RE particle number density and improving their uniformity of distribution in the additively formed magnesium alloy, thereby significantly enhancing the alloy's microstructure stability. This method provides a novel approach for the preparation of magnesium rare earth alloy wires and high thermal stability additively formed magnesium alloys.

[0010] Specifically, this is achieved through the following technical solutions:

[0011] This invention provides a magnesium rare earth alloy wire for additive manufacturing with high structural stability. The wire has the following composition by mass percentage: rare earth element RE: 10.0-15.0%, aluminum Al: 0.5-5.0%, manganese Mn: 0.2-2.0%, other individual impurity elements: ≤0.1%, total other impurity elements: ≤0.2%, and the balance is magnesium Mg.

[0012] The publicly reported magnesium rare earth alloy compositions used in additive manufacturing are mainly Mg-Gd-Y-Zr and Mg-Gd-Y-Zn-Zr alloy series. The main reinforcing phase in these alloys is the Mg-RE phase (such as Mg...).24 (e.g., RE5, Mg3RE, Mg5RE, etc.), but the Mg-RE phase dissolves into the Mg matrix at high temperatures, losing its strengthening effect. Therefore, existing magnesium rare earth alloys for additive manufacturing lack highly thermally stable reinforcing phase particles, resulting in low microstructural stability. Secondly, the high rare earth content and coarse, continuous rare earth phases in existing magnesium rare earth alloys for additive manufacturing lead to poor alloy plasticity, making the alloy ingot prone to cracking during the large plastic deformation process of wire forming. This invention first introduces highly thermally stable heterogeneous nucleation particles, Al2RE, into the ingot through Al-RE alloying. Al2RE particles not only improve the alloy's plasticity and toughness by refining the grains but also stably anchor at grain boundaries at high temperatures, inhibiting grain boundary migration and improving the alloy's microstructural stability. Furthermore, Mn alloying activates non-basal plane slip in the α-Mg matrix during plastic deformation, increasing the number of effective slip systems and improving the alloy's plastic deformation capability. Furthermore, due to the certain degree of lattice mismatch between Al2RE particles and the α-Mg matrix, dislocations are prone to accumulate and entangle at the two-phase interface, leading to crack initiation. The modification of the Al2RE / α-Mg phase interface by Mn elements can reduce the degree of lattice mismatch at the interface and further improve the plasticity of the alloy.

[0013] As one aspect of this invention, the rare earth element is two or more selected from gadolinium (Gd), yttrium (Y), neodymium (Nd), dysprosium (Dy), and erbium (Er). Two or more rare earth elements will form a large number of composite rare earth phases, which have a superior strengthening effect.

[0014] As one aspect of the present invention, the Al element content is 0.05 to 0.2 times the RE element content.

[0015] The strict limitation on the Al to RE ratio is because it directly affects the quantity and type of Al2RE phase formed, as well as the final strengthening effect. If the Al to RE ratio is too high, a large amount of RE will be consumed by Al, reducing the number of nano-rare earth strengthening phases in the alloy after aging treatment, resulting in a decrease in strength. When the Al to RE ratio is too low, the formed Al2RE phase is mostly a short rod-shaped or petal-shaped eutectic Al2RE phase, which has lower thermal stability than the granular Al2RE phase that preferentially precipitates in the melt at high temperatures. In addition, the number of Al2RE particles formed is also smaller, weakening the pinning effect on grain boundaries.

[0016] The present invention also provides a method for preparing the magnesium rare earth alloy wire, comprising the following steps:

[0017] S1. The raw materials are prepared according to the chemical element composition ratio of the magnesium rare earth alloy wire, smelted, cast and solidified to obtain ingot.

[0018] S2: The obtained ingot is homogenized, extruded to obtain wire, and then annealed and drawn to obtain the magnesium rare earth alloy wire.

[0019] In one aspect of this invention, in step S1, casting is performed under pulsed vibration with a vibration frequency of 10–100 Hz, an amplitude of 0.1–1 mm, and a peak acceleration of 1–10 g. The cooling rate during solidification is 0.5–5 °C / s. Pulsed vibration can assist in the nucleation of the Al-RE phase and control the solidification rate, promoting more Al-RE phase to become granular.

[0020] Applying pulsed vibrations during solidification can improve the uniformity of Al and RE element distribution in the melt, thereby reducing the size of the formed Al2RE phase and achieving a higher Al2RE phase number density. When the cooling rate is too fast, the alloy melt will rapidly supercool below the eutectic temperature, forming a large amount of eutectic Al2RE, which is detrimental to improving the alloy's microstructure stability. Therefore, controlling the cooling rate within a lower range can yield a larger number density of granular Al2RE phase.

[0021] As one aspect of the present invention, in step S2, the homogenization treatment is carried out at a temperature of 400–550°C for 8–24 hours.

[0022] As one aspect of the present invention, in step S2, the diameter of the extruded filament is 4.0 to 6.0 mm.

[0023] As one aspect of the present invention, in step S2, the annealing temperature is 200-400°C and the time is 1-5 hours.

[0024] As one aspect of the present invention, in step S2, the drawing temperature is 300-400°C, the deformation degree of each drawing is 5-10%, and after every 5-10 drawing passes, annealing is performed and drawing continues until the wire diameter is 1-1.5 mm.

[0025] As one aspect of the present invention, in step S2, the obtained magnesium rare earth alloy wire is further subjected to a peeling process, specifically: the obtained magnesium rare earth alloy wire is wound on the wire feeding assembly, rolled and then fed into the peeling mold for peeling, and then retracted through the wire drawing machine roller.

[0026] The present invention also provides an application of magnesium rare earth alloy wire in additive manufacturing, wherein the application is: the wire is melted and deposited using an additive manufacturing process to obtain a component, and then the magnesium rare earth alloy additive manufacturing component is subjected to solution treatment and aging treatment.

[0027] As one aspect of the present invention, the additive manufacturing process is any one of GTAW arc additive manufacturing, GMAW arc additive manufacturing, CMT arc additive manufacturing, and PAW arc additive manufacturing.

[0028] As one aspect of the present invention, the solution treatment temperature is 500-540℃ and the solution treatment time is 0.5-2h.

[0029] Through Al and Mn alloying, the additively manufactured magnesium rare earth alloy exhibits very fine grain size and second phase size. Therefore, unlike the traditional solution treatment process for cast magnesium rare earth alloys (solution time is generally 6-12 hours), the additively manufactured magnesium rare earth alloy prepared by this invention has a short solution time, with second phase re-dissolution achieved in 0.5-2 hours.

[0030] As one aspect of the present invention, the aging temperature of the aging treatment is 200-250℃, and the aging time is 10-20h.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) This invention introduces Al2RE particles with high number density, small size and high thermal stability into magnesium rare earth alloys for additive manufacturing by Al alloying and further combining formula optimization and process optimization. Mn is used to improve the interfacial bonding strength between Al2RE particles and α-Mg matrix, which effectively improves the microstructure stability of magnesium rare earth alloys for additive manufacturing.

[0033] 2) The use of Mn alloy activates the non-basal plane slip of magnesium rare earth alloy for additive manufacturing. Combined with the grain refinement effect of Al2RE particles, the plasticity and toughness of magnesium rare earth alloy are greatly improved, and the plastic deformation ability of magnesium rare earth alloy ingots during the wire making process is improved. The present invention can produce continuous, small-diameter magnesium rare earth alloy additive manufacturing wires.

[0034] 3) By crushing and dispersing Al2RE particles through wire-making processes such as extrusion and drawing, the uniformity of Al2RE particle distribution in magnesium rare earth alloy wire is greatly improved, thereby improving the uniformity of Al2RE distribution in additive manufacturing magnesium rare earth alloy and improving the mechanical properties of additive manufacturing magnesium rare earth alloy. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention. Attached Figure Description

[0036] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0037] Figure 1 Metallographic photograph of the arc-fused wire additive magnesium rare-earth alloy prepared in Example 1 after being held at 500°C for 10 hours.

[0038] Example 1

[0039] Preparation of magnesium rare earth alloy ingots:

[0040] The chemical composition and mass percentage of the prepared ingot were as follows: Gd: 7.0%, Y: 3.0%, Al: 0.5%, Mn: 0.2%, Mg: balance. Raw materials were prepared according to the chemical element composition ratios of the magnesium rare earth alloy wire and smelted. The raw materials were pure Mg ingot, Mg-Gd master alloy, Mg-Y master alloy, pure Al ingot, and Mg-Mn master alloy. The smelting temperature was 740℃, and the casting temperature was 720℃. Pulse vibration was used during casting with a vibration frequency of 10Hz, an amplitude of 0.1mm, a peak acceleration of 1g, and a solidification rate of 0.5℃ / s.

[0041] Preparation of magnesium rare earth alloy wire:

[0042] The ingot was homogenized and annealed at 400℃ for 24 hours, and then extruded to obtain a wire with a diameter of 4 mm. The wire was then annealed at 200℃ for 5 hours. The wire was then drawn at 300℃, with a deformation of 5% per drawing pass. After every 5 drawing passes, the wire was annealed and then drawn again until the wire diameter was 1 mm. The resulting magnesium rare earth alloy wire was wound onto a wire feeding assembly, rolled, and then fed into a stripping die for stripping. Finally, the wire was retrieved through the drawing machine rollers.

[0043] Magnesium rare earth alloy additive manufacturing and post-processing:

[0044] Arc-fused wire additive manufacturing was performed using CMT equipment to prepare deposited parts, which were then subjected to heat treatment. The solution temperature was 500℃, and the solution time was 2 hours. The aging temperature was 200℃, and the aging time was 20 hours.

[0045] Experiments showed that the wire exhibited no breakage during preparation, good plasticity, and a single strand length of 1 km. The grain size of the magnesium rare-earth alloy produced by arc-fused wire additive manufacturing was 12 μm, and after holding at 500℃ for 10 hours, the grain size only grew to 15 μm. Figure 1 As shown, the tissue exhibits excellent stability.

[0046] Example 2

[0047] Preparation of magnesium rare earth alloy ingots:

[0048] The chemical composition and mass percentage of the prepared ingot were as follows: Gd: 8.0%, Nd: 3.0%, Al: 1.1%, Mn: 0.5%, Mg: balance. Raw materials were prepared according to the chemical element composition ratios of the magnesium rare earth alloy wire and smelted. The raw materials were pure Mg ingot, Mg-Gd master alloy, Mg-Nd master alloy, pure Al ingot, and Mg-Mn master alloy. The smelting temperature was 740℃, and the casting temperature was 720℃. Pulse vibration was used during casting with a vibration frequency of 50Hz, an amplitude of 0.5mm, a peak acceleration of 5g, and a solidification rate of 2℃ / s.

[0049] Preparation of magnesium rare earth alloy wire:

[0050] The ingot was homogenized and annealed at 450℃ for 20 hours, and then extruded to obtain a wire with a diameter of 5 mm. The wire was then annealed at 250℃ for 4 hours. The wire was then drawn at 320℃, with a deformation of 6% per drawing pass. After every 6 drawing passes, the wire was annealed and then drawn again until the wire diameter reached 1.2 mm. The resulting magnesium rare earth alloy wire was wound onto a wire feeding assembly, rolled, and then fed into a stripping die for stripping. Finally, it was retrieved through the rollers of a wire drawing machine.

[0051] Magnesium rare earth alloy additive manufacturing and post-processing:

[0052] Arc-fused wire additive manufacturing was performed using CMT equipment to prepare the deposited part, which was then subjected to heat treatment. The solution temperature was 510℃, and the solution time was 1.5 h. The aging temperature was 210℃, and the aging time was 16 h.

[0053] Experiments showed that the wire did not break during preparation, exhibited good plasticity, and had a single strand length of 1.1 km. The magnesium rare earth alloy produced by arc-fused wire additive manufacturing had a grain size of 11 μm, and after holding at 500℃ for 10 h, the grain size only grew to 14 μm, demonstrating excellent microstructural stability.

[0054] Example 3

[0055] Preparation of magnesium rare earth alloy ingots:

[0056] The chemical composition and mass percentage of the prepared ingot were as follows: Gd: 8.0%, Dy: 4.0%, Al: 1.8%, Mn: 1.0%, Mg: balance. Raw materials were prepared according to the chemical element composition ratios of the magnesium rare earth alloy wire and smelted. The raw materials were pure Mg ingot, Mg-Gd master alloy, Mg-Dy master alloy, pure Al ingot, and Mg-Mn master alloy. The smelting temperature was 740℃, and the casting temperature was 720℃. Pulse vibration was used during casting with a vibration frequency of 70Hz, an amplitude of 0.7mm, a peak acceleration of 7g, and a solidification rate of 4℃ / s.

[0057] Preparation of magnesium rare earth alloy wire:

[0058] The ingot was homogenized and annealed at 500℃ for 15 hours, and then extruded to obtain a wire with a diameter of 5.5 mm. The wire was then annealed at 300℃ for 3 hours. The wire was then drawn at 360℃, with a deformation of 8% per drawing pass. After every 8 drawing passes, the wire was annealed and then drawn again until the wire diameter reached 1.3 mm. The resulting magnesium rare earth alloy wire was wound onto a wire feeding assembly, rolled, and then fed into a stripping die for stripping. Finally, it was retrieved through the rollers of a wire drawing machine.

[0059] Magnesium rare earth alloy additive manufacturing and post-processing:

[0060] Arc-fused wire additive manufacturing was performed using CMT equipment to prepare the deposited part, which was then subjected to heat treatment. The solution temperature was 530℃, and the solution time was 1 hour. The aging temperature was 230℃, and the aging time was 12 hours.

[0061] Experiments showed that the wire did not break during preparation, exhibited good plasticity, and had a single strand length of 1 km. The grain size of the magnesium rare earth alloy produced by arc-fused wire additive manufacturing was 11 μm, and after holding at 500℃ for 10 h, the grain size only grew to 13 μm, demonstrating excellent microstructural stability.

[0062] Example 4

[0063] Preparation of magnesium rare earth alloy ingots:

[0064] The chemical composition and mass percentage of the prepared ingot were as follows: Gd: 10.0%, Er: 5.0%, Al: 3%, Mn: 2.0%, Mg: balance. Raw materials were prepared according to the chemical element composition ratios of the magnesium rare earth alloy wire and smelted. The raw materials were pure Mg ingot, Mg-Gd master alloy, Mg-Er master alloy, pure Al ingot, and Mg-Mn master alloy. The smelting temperature was 740℃, and the casting temperature was 720℃. Pulse vibration was used during casting with a vibration frequency of 100Hz, an amplitude of 1mm, a peak acceleration of 10g, and a solidification rate of 5℃ / s.

[0065] Preparation of magnesium rare earth alloy wire:

[0066] The ingot was homogenized and annealed at 550℃ for 8 hours, and then extruded to obtain a wire with a diameter of 6 mm. The wire was then annealed at 400℃ for 1 hour. The wire was then drawn at 400℃, with a deformation of 10% per drawing pass. After every 10 drawing passes, the wire was annealed and then drawn again until the wire diameter reached 1.5 mm. The resulting magnesium rare earth alloy wire was wound onto a wire feeding assembly, rolled, and then fed into a stripping die for stripping. Finally, it was retrieved through the rollers of a wire drawing machine.

[0067] Magnesium rare earth alloy additive manufacturing and post-processing:

[0068] Arc-fused wire additive manufacturing was performed using CMT equipment to prepare the deposited part, which was then subjected to heat treatment. The solution temperature was 540℃, and the solution time was 0.5 h. The aging temperature was 250℃, and the aging time was 10 h.

[0069] Experiments showed that the wire did not break during preparation, exhibited good plasticity, and had a single strand length of 1.2 km. The magnesium rare earth alloy produced by arc-fused wire additive manufacturing had a grain size of 13 μm, and after holding at 500℃ for 10 h, the grain size only grew to 15 μm, demonstrating excellent microstructural stability.

[0070] Comparative Example 1

[0071] The preparation and usage methods of the magnesium rare earth alloy wire described in this comparative example are basically the same as those in Example 1, except that the wire does not contain Al, and the mass ratios of other elements are the same as in Example 1.

[0072] Experiments revealed that during the wire-making process, the length of a single wire decreased to only 200m. This indicates that the lack of Al alloying resulted in an insufficient number of effective heterogeneous nucleation sites in the alloy, leading to coarse grain size and reduced plastic deformation capacity of the wire.

[0073] The grain size of the magnesium rare earth alloy produced by arc-fused wire additive manufacturing is 120 μm. After holding at 500℃ for 10 h, the grain size grows to 600 μm, resulting in poor microstructural stability. This is mainly due to the loss of the pinning effect of Al2RE particles on the grain boundaries, leading to poor microstructural stability in the arc-fused wire additive magnesium rare earth alloy.

[0074] Comparative Example 2

[0075] The preparation and usage methods of the magnesium rare earth alloy wire described in this comparative example are basically the same as those in Example 1, except that the wire does not contain Mn element, and the mass ratio of other elements is the same as in Example 1.

[0076] Experiments showed that during the wire-making process, the length of a single wire decreased to only 100m. This indicates that the lack of Mn alloying inhibited non-basal plane slip during plastic deformation, thus reducing the wire's plastic deformation capacity.

[0077] The grain size of the magnesium rare earth alloy produced by arc-fused wire additive manufacturing is 15 μm, which grows to 18 μm after holding at 500℃ for 10 h. However, the mechanical properties of the arc-fused wire additive alloy decrease. This is mainly due to the large number of dislocations accumulating at the phase interface between Al2RE particles and the α-Mg matrix, leading to premature microcrack initiation and reduced mechanical properties of the arc-fused wire additive magnesium rare earth alloy.

[0078] Comparative Example 3

[0079] The preparation and usage methods of the magnesium rare earth alloy wire described in this comparative example are basically the same as those in Example 1, except that the Al content in the wire is only 0.3%, that is, the Al content is only 0.03% of the RE content. The mass ratios of other elements are the same as in Example 1.

[0080] Experiments revealed that during the wire-making process, the length of a single wire decreased to only 700m. This indicates that the low Al content resulted in insufficient effective heterogeneous nucleation sites in the alloy, leading to coarse grain size and reduced plastic deformation capacity of the wire.

[0081] The grain size of the magnesium rare earth alloy produced by arc-fused wire additive manufacturing is 30 μm. After holding at 500℃ for 10 h, the grain size grows to 50 μm, resulting in poor microstructural stability. This is mainly due to the reduced pinning effect of Al2RE particles on grain boundaries, leading to poor microstructural stability of the arc-fused wire additive magnesium rare earth alloy.

[0082] Comparative Example 4

[0083] The preparation and use methods of the magnesium rare earth alloy wire described in this comparative example are basically the same as those in Example 1, except that pulse vibration was not applied during the solidification process of the cast billet.

[0084] Experiments showed that during the wire-making process, the length of a single wire decreased to only 500m. This indicates that, due to the absence of pulse vibration, the Al2RE heterogeneous nucleation core size in the alloy became coarse, resulting in larger alloy grain size and reduced plastic deformation capacity of the wire.

[0085] The grain size of the magnesium rare earth alloy produced by arc-fused wire additive manufacturing is 30 μm. After holding at 500℃ for 10 h, the grain size grows to 50 μm, resulting in poor microstructural stability. This is mainly due to the weakened pinning effect of Al2RE particles on grain boundaries, leading to poor microstructural stability of the arc-fused wire additive magnesium rare earth alloy.

[0086] Comparative Example 5

[0087] The preparation and use methods of the magnesium rare earth alloy wire described in this comparative example are basically the same as those in Example 1, except that the solidification rate of the billet is controlled during the solidification process, and the solidification rate of the billet is 10℃ / s.

[0088] Experiments revealed that during the wire-making process, the length of a single wire decreased to only 400m. This indicates that due to the rapid solidification rate, Al2RE in the alloy mainly exists in the form of a eutectic phase, and the alloy grain size becomes coarser, reducing the wire's plastic deformation capacity.

[0089] The grain size of the magnesium rare earth alloy produced by arc-fused wire additive manufacturing is 50 μm. After holding at 500℃ for 10 h, the grain size grows to 80 μm, resulting in poor microstructural stability. This is mainly due to the weakened pinning effect of Al2RE particles on grain boundaries, leading to poor microstructural stability of the arc-fused wire additive magnesium rare earth alloy.

[0090] Comparative Example 6

[0091] The preparation and usage methods of the magnesium rare earth alloy wire described in this comparative example are basically the same as those in Example 1, except that the solid solution time of the arc-fused magnesium rare earth alloy additive manufacturing process is 0.4 h.

[0092] Experiments showed that the grain size of the magnesium rare earth alloy produced by arc-fused wire additive manufacturing was 12 μm, and the grain size grew to 14 μm after holding at 500℃ for 10 h. Compared with the examples, the alloy in this comparative example had lower mechanical properties, mainly due to the short solution time, resulting in the presence of more undissolved second phases in the alloy.

[0093] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A magnesium rare earth alloy wire for additive manufacturing with high microstructural stability, characterized by, The components include the following elements with mass fractions: Rare earth element RE: 10.0-15.0%, aluminum Al: 0.5-5.0%, manganese Mn: 0.2-2.0%, and the balance being magnesium Mg; The Al element content is 0.05-0.2 of the RE element content; The preparation method of the magnesium rare earth alloy wire material for additive manufacturing includes the following steps: S1. Melting raw materials configured according to the chemical element composition ratio of the magnesium rare earth alloy wire material for additive manufacturing, casting and solidifying to obtain an ingot; S2. Homogenizing the obtained ingot, extruding to obtain a wire material, and then annealing and drawing to obtain the magnesium rare earth alloy wire material; In step S1, the casting is performed under pulse vibration, the vibration frequency is 10-100 Hz, the amplitude is 0.1-1 mm, and the vibration peak acceleration is 1-10 g; In step S1, the cooling speed during solidification is 0.5-5 ℃ / s.

2. The magnesium rare earth alloy wire for additive manufacturing according to claim 1, characterized by, The rare earth element RE includes two or more of gadolinium Gd, yttrium Y, neodymium Nd, dysprosium Dy, and erbium Er.

3. The magnesium rare earth alloy wire for additive manufacturing according to claim 1, characterized by, In step S2, the homogenization treatment temperature is 400-550 ℃, and the time is 8-24 h.

4. The magnesium rare earth alloy wire for additive manufacturing according to claim 1, characterized by, In step S2, the annealing temperature is 200-400 ℃, and the time is 1-5 h.

5. The magnesium rare earth alloy wire for additive manufacturing according to claim 1, characterized by, In step S2, the drawing temperature is 300-400 ℃, the deformation degree of each drawing is 5-10%, the wire material is annealed after drawing for 5-10 passes and then continues to be drawn, until the diameter of the wire material is 1-1.5 mm.

6. Application of the magnesium rare earth alloy wire material for additive manufacturing according to claim 1 in additive manufacturing shaping.

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