Au-Pt-Pd alloy wire with high strength and ultralow magnetic susceptibility as well as preparation method and application of Au-Pt-Pd alloy wire

Abstract

The invention relates to a high-strength and ultralow-magnetic susceptibility Au-Pt-Pd alloy wire as well as a preparation method and application thereof, and relates to the technical field of new materials. According to the preparation method, through the unique process combination of smelting, homogenization, severe plastic deformation and specific aging, the problem of contradiction between the alloy strength and the ultralow magnetic susceptibility is successfully solved, and the prepared Au-Pt-Pd alloy wire has the strength and the ultralow magnetic susceptibility far higher than those of a traditional Au-Pt alloy and still keeps certain plasticity.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, specifically to a high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire, its preparation method, and its applications. Background Technology

[0002] It combines high strength and ultra-low magnetic susceptibility (absolute value ≤10). -6 Au-Pt alloys are crucial structural-functional integrated materials urgently needed in high-end biomedical fields, such as MRI-compatible guidewires and embolization coils. While widely studied Au-Pt alloys can achieve ultra-low magnetic susceptibility through compositional design, their mechanical properties (such as hardness, typically only 150-180 HV) are insufficient for practical applications. Traditional methods of controlling the magnetic susceptibility of ferro / paramagnetic matrix alloys by adding diamagnetic elements have limited effectiveness. Adding small amounts of paramagnetic elements (such as Pt) to a diamagnetic matrix (such as Au) can more effectively and precisely control the magnetic susceptibility closer to zero, but the strength of such alloys often becomes a new bottleneck. Researchers have proposed a gold-platinum alloy for quality control inertial sensors used in space gravitational wave detection; although it is an ultra-low magnetic susceptibility Au-Pt alloy, its mechanical properties are poor, with a hardness of only 150 HV. Other researchers have studied the amplitude modulation decomposition control problem of Au-Pt alloys, significantly improving the alloy strength, but its magnetic susceptibility has not been optimized. Therefore, it is of great significance to develop an alloy material that can simultaneously achieve high strength and ultra-low magnetic susceptibility and its reliable preparation process. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for preparing high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire. This method, through a unique combination of "melting + homogenization + large plastic deformation + specific aging" processes, successfully solves the contradiction between alloy strength and ultra-low magnetic susceptibility. As a result, the prepared Au-Pt-Pd alloy wire has much higher strength and ultra-low magnetic susceptibility than traditional Au-Pt alloys, while still maintaining a certain degree of plasticity.

[0004] This invention provides a method for preparing high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire, comprising the following steps: Melting casting: Weigh the raw materials, pickle them, melt them, and obtain ingots; Homogenization treatment: The ingot is heat-treated under vacuum and then water-quenched to obtain an annealed ingot. Large plastic deformation: The annealed ingot is rolled into a bar, recrystallized and annealed, and then drawn into a wire. Aging treatment: The filament is subjected to aging heat treatment under vacuum and sealed conditions, followed by heat preservation and water cooling.

[0005] The preparation method of this invention does not involve die forging; instead, it directly cold-rolls the homogenized ingot (because the plastic processing temperature of this invention is room temperature). After cold rolling, to ensure the alloy remains in a single-phase state, stress-relief annealing is performed at the same temperature as the homogenization. After stress relief, the alloy is cold-drawn through a die using a wire drawing machine to finally obtain wire of the target size. During this process, a large number of dislocations are introduced through the large plastic deformation step, providing precipitation sites for the formation of precipitates, facilitating the precipitation of the second phase, strengthening the alloy, and adjusting the alloy's magnetic susceptibility. Furthermore, since the plastic processing temperature of this invention is room temperature, stress-relief annealing is performed through a recrystallization annealing step to ensure the alloy's machinability during processing, followed by water cooling, and then processing continues to the target size wire. This not only eliminates the solution treatment step after plastic processing in conventional techniques but also significantly increases hardness and controls the amplitude-modulated decomposition phase.

[0006] In one embodiment, the raw materials in the melting and casting step include gold, platinum, and palladium; The smelting process includes: smelting under a protective atmosphere using a current of 300-350A until the composition of the ingot is uniform.

[0007] The current technology suffers from the drawback of simultaneously achieving ultra-low magnetic susceptibility and good mechanical properties. Specifically, while existing Au-Pt alloys can achieve ultra-low magnetic susceptibility (≤10) through composition design and process control, this presents a challenge. -6 However, its mechanical properties are significantly insufficient, making it difficult to meet the requirements of high-end applications for comprehensive material performance. This invention adds Pd to the Au-Pt alloy, which can effectively prevent heterogeneous precipitation from significantly affecting the alloy's magnetic susceptibility. Simultaneously, Pd, as a solid solution strengthening element for Au and Pt, can also improve the alloy's strength, achieving mechanical-magnetic compatibility.

[0008] In one embodiment, the raw materials contain 55-70 wt.% gold, 20-35 wt.% platinum, and 5-15 wt.% palladium by mass.

[0009] In one embodiment, the vacuum sealing condition in the homogenization step includes a vacuum degree of (4-6) × 10⁻⁶. -3 Pa; The heat treatment temperature is 900-1200℃, and the holding time is 5-10h.

[0010] In one embodiment, during the large plastic deformation step, the maximum recrystallization annealing temperature is 900-1200℃, and the holding time is 1-2 hours; the total deformation is ≥90%.

[0011] In one embodiment, in the large plastic deformation step, the rolling is cold rolling with a single-pass deformation amount of 5% to 10%, and the drawing has a single-pass deformation amount of 5% to 15%.

[0012] In one embodiment, the aging process involves a heat treatment temperature of 100-800°C and a holding time of 0.5-5 hours.

[0013] The present invention also provides a high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire obtained by the preparation method described above.

[0014] In one embodiment, the high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire has a tensile strength ≥900MPa, a yield strength ≥850MPa, and a magnetic susceptibility of ±1.00×10⁻⁶. -6 .

[0015] The present invention also provides the application of the high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire in medical devices.

[0016] The present invention also provides a guidewire for MRI, comprising the aforementioned high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire.

[0017] The present invention also provides an embolization coil, comprising the high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention successfully solves the problem of the contradiction between alloy strength and ultra-low magnetic susceptibility by optimizing the process combination of "melting + homogenization + large plastic deformation + specific aging".

[0019] (1) High strength: The alloy has high strength by introducing work hardening through large plastic deformation and combining it with amplitude modulation analysis to achieve high strength. The Au-25Pt-10Pd alloy has an aging peak hardness of 334 HV, a tensile strength of 930 MPa, and a yield strength of 855 MPa, which are far higher than those of traditional Au-Pt alloys (150~170 HV).

[0020] (2) Ultra-low magnetic susceptibility: Using diamagnetic Au as the matrix, the magnetic susceptibility of the alloy is precisely controlled to near zero by adding specific proportions of paramagnetic Pt and Pd. The magnetic susceptibility of the Au-25Pt-10Pd alloy under optimal aging conditions can reach -0.47×10⁻⁶. -6 (ppm), which is very close to the magnetic susceptibility of human tissue, meeting MRI compatibility requirements.

[0021] (3) Excellent comprehensive performance: While achieving high strength, the alloy still maintains a certain degree of plasticity (elongation > 4%). Its comprehensive mechanical properties and magnetic susceptibility are superior to most ultra-low magnetic susceptibility alloys reported to date.

[0022] (4) Clear mechanism: Advanced characterization methods such as TEM confirmed that its strengthening mechanism is the interaction between the elastic stress field of the coherent nanoprecipitates generated by amplitude modulation decomposition and the dislocations, and the change in magnetic susceptibility originates from the precipitation of paramagnetic Pt-rich phase. The performance regulation mechanism is clear and highly reproducible. Attached Figure Description

[0023] Figure 1 A schematic diagram of Au-25Pt-10Pd alloy ingots obtained by arc melting; Figure 2 SEM image of Au-25Pt-10Pd alloy ingot after homogenization annealing; Figure 3 A schematic diagram of cold-drawn Au-25Pt-10Pd alloy wire with a diameter of 0.5 mm; Figure 4 TEM image of Au-25Pt-10Pd alloy; Figure 5 A schematic diagram of Au-30Pt-10Pd alloy ingots obtained by arc melting; Figure 6 SEM image of Au-30Pt-10Pd alloy ingot after homogenization annealing; Figure 7 A schematic diagram of a cold-drawn Au-30Pt-10Pd alloy wire with a diameter of 0.5 mm; Figure 8 TEM image of Au-30Pt-10Pd alloy; Figure 9 The graph shows the hardness change trend of Au-25Pt-10Pd alloy after holding at different temperatures for 1 hour. Figure 10 The graph shows the hardness variation trend of Au-25Pt-10Pd alloy under different holding times at a holding temperature of 600℃. Figure 11 The graph shows the trend of hardness change of each wire prepared in "Step 1" of Comparative Example 1 after being kept at different temperatures for 1 hour. Detailed Implementation

[0024] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Unless otherwise specified, all reagents, materials, and equipment used in this embodiment are commercially available; unless otherwise specified, all test methods are conventional test methods in this field.

[0027] Example A method for preparing high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire.

[0028] Step 1, Batching and Melting: Select high-purity (≥99.99%) Au, Pt and Pd metal raw materials, weigh them according to the proportion, and after acid washing and cleaning, melt them in an electric arc furnace under argon protection and repeatedly turn them 4 to 7 times to obtain alloy ingots with uniform composition.

[0029] Step 2, Homogenization Annealing: The ingot is sealed in a vacuum chamber with a vacuum degree of 5×10⁻⁶ using a vacuum sealing machine. -3 In a quartz tube containing Pa, a homogenization annealing treatment is performed at 900~1200℃ for 5~10h, followed by water cooling to eliminate dendrite segregation in the ingot.

[0030] Step 3, Large Plastic Deformation: The homogenized ingot is subjected to 10-20 passes of cold rolling (5%-10% deformation per pass) and drawing (5%-15% deformation per pass), with a total deformation of over 90%. An annealing treatment is performed between cold rolling and drawing to eliminate work hardening.

[0031] Step 4: Aging Treatment: The cold-drawn alloy wire is aged in a resistance furnace. This process induces amplitude modulation decomposition in the Au-Pt-Pd alloy, producing nanoscale Au-rich and Pt-rich phases, thereby significantly strengthening the alloy.

[0032] In step three, the annealing temperature is 900~1200℃ and the annealing time is 1~2 h.

[0033] In step four, the aging treatment temperature is 100~800℃ and the aging time is 0.5~5h.

[0034] Application Example 1 High-strength, ultra-low magnetic susceptibility Au-25Pt-10Pd alloy wire and its preparation method.

[0035] The preparation was carried out according to the examples, and the specific operations are as follows: Step 1: Ingredients: Weigh out 65 wt.% pure Au, 25 wt.% pure Pt, and 10 wt.% pure Pd, for a total weight of 100 g.

[0036] Step 2, Smelting: After pickling, the raw materials are placed in an electric arc melting furnace and smelted for 1-2 minutes under 0.5MPa argon protection using a 300A current. The furnace is then repeatedly turned and smelted 5 times to obtain a uniform ingot.

[0037] Step 3, Homogenization Annealing: Seal the ingot under a vacuum of 5×10⁻⁶. -3 The alloy was obtained by holding it at 1100℃ for 8 hours in a quartz tube containing Pa, followed by water quenching.

[0038] Step 4, Large Plastic Deformation: The annealed ingot is rolled into a bar with a diameter of approximately 1.35 mm. Intermediate recrystallization annealing is then performed, specifically by heating the annealing furnace to 1100℃, placing the bar into the furnace, and holding it at that temperature for 1 hour. Finally, through multiple drawing passes, a wire with a diameter of 0.5 mm is produced, with a total deformation exceeding 90%.

[0039] Step 5, Aging Treatment: The filament is encapsulated in a vacuum quartz tube and aged at 600℃ for 1.5 hours, then water-cooled.

[0040] Step Six: The microhardness of the alloy in the state of Step Five was measured to be 334 HV using a Vickers hardness tester; the tensile strength was measured to be 930 MPa, the yield strength to be 855 MPa, and the elongation to be 6.22% using a universal tensile testing machine; the magnetic susceptibility was measured to be -0.47 × 10⁻⁶ using a PPMS comprehensive property testing system. -6 .

[0041] Figure 1 The Au-25Pt-10Pd alloy ingot is obtained by arc melting.

[0042] Figure 2 SEM image of Au-25Pt-10Pd alloy ingot after homogenization annealing.

[0043] Figure 3 It is a cold-drawn Au-25Pt-10Pd alloy wire with a diameter of 0.5 mm.

[0044] Figure 4 TEM image of Au-25Pt-10Pd alloy.

[0045] Application Example 2 High-strength, ultra-low magnetic susceptibility Au-30Pt-10Pd alloy wire and its preparation method Step 1, Ingredients: Weigh out 60 wt.% pure Au, 30 wt.% pure Pt, and 10 wt.% pure Pd, for a total weight of 20 g.

[0046] Step 2, Smelting: After pickling, the raw materials are placed in an electric arc melting furnace and repeatedly smelted 7 times with a current of 350A under argon protection of 0.5MPa to obtain a uniform ingot.

[0047] Step 3, Homogenization Annealing: Seal the ingot under a vacuum of 5×10⁻⁶. -3 The alloy was obtained by holding it at 1200℃ for 10 hours in a quartz tube containing Pa, followed by water quenching.

[0048] Step 4, Large Plastic Deformation: The annealed ingot is rolled into bars with a diameter of approximately 1.35 mm. Intermediate recrystallization annealing at 1100℃ / 1h is then performed. Finally, the bars are drawn in multiple passes to produce wires with a diameter of 0.5 mm, with a total deformation exceeding 90%.

[0049] Subsequently, recrystallization annealing is performed to eliminate processing stress and obtain a uniform microstructure. Specifically, the recrystallization annealing involves heating the annealing furnace to 1100°C, placing the bar into the furnace, and then holding it at that temperature for 1 hour. Finally, the bar is produced into a 0.5 mm diameter wire through multiple cold drawing passes (with intermediate annealing).

[0050] Step 5, Aging Treatment: The filament is encapsulated in a vacuum quartz tube and aged at 650℃. After holding at this temperature for 1 hour, it is then water-cooled.

[0051] Step Six: The microhardness of the alloy in the state of Step Five was measured to be 365 HV using a Vickers hardness tester; the tensile strength was measured to be 1020 MPa, the yield strength to be 935 MPa, and the elongation to be 4.5% using a universal tensile testing machine; the magnetic susceptibility was measured to be -0.33 × 10⁻⁶ using a PPMS comprehensive property testing system. -6 .

[0052] Figure 5 The Au-30Pt-10Pd alloy ingot is obtained by arc melting.

[0053] Figure 6 SEM image of Au-30Pt-10Pd alloy ingot after homogenization annealing.

[0054] Figure 7It is a cold-drawn Au-30Pt-10Pd alloy wire with a diameter of 0.5 mm.

[0055] Figure 8 TEM image of Au-30Pt-10Pd alloy.

[0056] Comparative Example 1 An Au-25Pt-10Pd alloy wire and its preparation method.

[0057] The preparation method is basically the same as that in Application Example 1, except that after "Step 4, Large Plastic Deformation", a solution treatment is performed at 1100℃ for 3 hours, followed by aging heat treatment at different temperatures from 200℃ to 700℃.

[0058] Since the research and development objective of this invention is to obtain alloy materials that possess both high strength and ultra-low magnetic susceptibility, and precious metals are highly valuable, this process only uses a Vickers hardness tester to test the hardness (hardness changes in the same direction as strength) to reflect the strength change. Because the mechanical properties of the alloy wires prepared in this comparative example remain unchanged, it is unnecessary to measure the magnetic susceptibility. The following are the hardness values ​​of the various alloy wires prepared in this comparative example:

[0059] As can be seen from the data in the table above, the hardness of the alloy after annealing at 200~600℃ is basically unchanged compared with the processed state (i.e., the solution state). The hardness drops significantly after 700℃ due to the recovery recrystallization of the alloy.

[0060] II. Preparation Method: Compared with "Step 1" of Comparative Example 1, the only difference is the elimination of "solution treatment," and the direct aging heat treatment following "Step 4, Large Plastic Deformation." The hardness change trends of the prepared wires after holding at different temperatures for 1 hour are as follows: Figure 9 As shown.

[0061] After treatment at different temperatures, it was found that the hardness reached its peak at 600℃. Therefore, further research was conducted on different holding times at 600℃. Ultimately, it was concluded that the alloy exhibited optimal mechanical properties at 600℃ for 1.5 hours. Figure 10 As shown.

[0062] The hardness change trends of the various wires prepared in "Step 1" of Comparative Example 1 after being kept at different temperatures for 1 hour are as follows: Figure 11 As shown. With Figure 9 The displayed changes in hardness present a stark contrast.

[0063] Comparative Example 2 An Au-30Pt-10Pd alloy wire and its preparation method.

[0064] The preparation method is basically the same as that in Application Example 2, except that after "Step 4, Large Plastic Deformation", a solution treatment is performed at 1100℃ for 3 hours, followed by aging heat treatment at different temperatures from 200℃ to 700℃.

[0065] Since the research and development objective of this invention is to obtain alloy materials that possess both high strength and ultra-low magnetic susceptibility, and precious metals are highly valuable, this process only uses a Vickers hardness tester to test the hardness (hardness changes in the same direction as strength) to reflect the strength change. Because the mechanical properties of the alloy wires prepared in this comparative example remain unchanged, it is unnecessary to measure the magnetic susceptibility. The following are the hardness values ​​of the various alloy wires prepared in Comparative Example 2:

[0066] II. Preparation Method: Compared with "Step 1" of Comparative Example 2, the only difference is that the "solution treatment" is omitted, and aging heat treatment is performed directly after "Step 4, Large Plastic Deformation". The hardness of each wire obtained is tested using a Vickers hardness tester, and the results are shown in the table below.

[0067]

[0068] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire, characterized in that, Includes the following steps: Melting casting: Weigh the raw materials, pickle them, melt them, and obtain ingots; Homogenization treatment: The ingot is heat-treated under vacuum and then water-quenched to obtain an annealed ingot. Large plastic deformation: The annealed ingot is rolled into a bar, recrystallized and annealed, and then drawn into a wire. Aging treatment: The filament is subjected to aging heat treatment under vacuum and sealed conditions, followed by heat preservation and water cooling.

2. The preparation method according to claim 1, characterized in that, In the melting and casting step, the raw materials include gold, platinum, and palladium; The smelting process includes: smelting under a protective atmosphere using a current of 300-350A until the composition of the ingot is uniform.

3. The preparation method according to claim 1, characterized in that, In the homogenization process, the vacuum sealing conditions include: a vacuum degree of (4-6)×10⁻⁶. -3 Pa; The heat treatment temperature is 900-1200℃, and the holding time is 5-10h.

4. The preparation method according to claim 1, characterized in that, In the large plastic deformation step, the maximum temperature of the recrystallization annealing is 900-1200℃, and the holding time is 1-2h; the total deformation is ≥90%.

5. The preparation method according to claim 1, characterized in that, In the aging process, the aging heat treatment temperature is 100-800℃, and the holding time is 0.5-5h.

6. The high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire obtained by the preparation method according to any one of claims 1-5.

7. The high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire according to claim 6, characterized in that, The high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire has a tensile strength ≥900MPa, a yield strength ≥850MPa, and a magnetic susceptibility of ±1.00×10⁻⁶. -6 .

8. The application of the high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire as described in any one of claims 6-7 in medical devices.

9. A guidewire for MRI, characterized in that, Includes the high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire as described in any one of claims 6-7.

10. An embolization coil, characterized in that, Includes the high-strength, ultra-low magnetic susceptibility Au-Pt-Pd alloy wire as described in any one of claims 6-7.

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