A high-hardness and high-strength palladium-silver-copper-nickel quaternary alloy rod for a probe and a preparation method thereof

Abstract

This invention relates to a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes and its preparation method. The elemental composition of the palladium-silver-copper-nickel quaternary alloy rod, by mass percentage, is: Pd 30-38%, Cu 40-46%, Ag 10-20%, Ni 8-15%; the sum of the mass of Ag and Ni is 18-30%, and the sum of the mass of Pd and Ni is 41-50%. The heat-treated palladium-silver-copper-nickel quaternary alloy rod has a hardness greater than 300 HV and a strength greater than 1000 MPa. The invention utilizes relatively low-cost nickel as a key strengthening element, synergistically strengthening it with silver and copper in an alloy matrix with a low palladium content. Combined with an efficient and high-quality forming process, a balance between high hardness and high strength is achieved in the alloy while maintaining controllable costs, meeting the stringent requirements of testing probes.

Description

Technical Field

[0001] This invention relates to the field of alloy technology for probes, specifically to a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes and its preparation method. Background Technology

[0002] In the testing of semiconductor integrated circuits and liquid crystal display devices, electrical contact and probe materials need to possess high conductivity, high hardness, excellent wear resistance, resistance to high-temperature softening, and good ductility to meet the reliability requirements of high-frequency, high-current testing. Traditional precious metal alloys, such as gold-based and platinum-based alloys, while possessing excellent chemical stability and conductivity, are expensive and have poor processing performance, hindering large-scale application. Therefore, palladium-based alloys, due to their relatively low cost and good overall performance, have gradually become a research hotspot in this field.

[0003] Currently, various palladium-based alloys, such as palladium-silver-copper alloys, have been developed for applications in electrical contacts and probes. The strength and hardness of palladium-silver-copper alloys can be improved through appropriate component ratios and aging treatment. However, existing palladium-silver-copper ternary alloys often require a palladium content exceeding 40% to achieve a hardness of over 300 HV and a strength greater than 1000 MPa. This fails to meet the requirements of semiconductor integrated circuit or liquid crystal display device testing, which demands reduced material costs while maintaining high material performance, achieving a balance between performance and cost control. For example, patent CN108699629B discloses a Pd-Cu-Ag-Re alloy that achieves high electrical conductivity (≥19.5% IACS) and hardness (≥350 HV) after age hardening by controlling the Pd:Cu ratio (1.09–1.6) and Pd:Ag ratio (3–6). However, this alloy requires a high palladium content (up to 45-55 wt%), and its high performance also relies on expensive rhenium, further increasing material costs.

[0004] Japanese Patent Publication No. JP5657881B2 discloses an Ag-Pd-Cu-In alloy. This alloy improves its work hardening ability by adding indium, but it is essentially a silver-based material (Ag 25–50 wt%). Although the palladium content is relatively low (Pd 25–50 wt%), the high silver content can easily lead to insufficient strength, making it difficult to meet the stringent requirements for comprehensive performance in test probe applications.

[0005] Therefore, there is an urgent need in this field for a palladium-based alloy that can achieve a balanced optimization of conductivity, hardness, and strength while keeping costs under control, in order to meet the application requirements of semiconductor test probes. Summary of the Invention

[0006] To address at least one of the aforementioned problems in the prior art, this invention provides a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes and its preparation method. By using relatively low-cost nickel as a key strengthening element, which works synergistically with silver and copper, strengthening is achieved in an alloy matrix with a low palladium content. Combined with an efficient and high-quality forming process, a balance between low resistivity, high hardness, and high strength of the alloy is achieved under controllable cost conditions, thus meeting the stringent requirements of test probes.

[0007] In one aspect of the present invention, a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes is provided, wherein the elemental composition of the palladium-silver-copper-nickel quaternary alloy rod, by mass percentage, is as follows:

[0008] Pd 30-38%,

[0009] Cu 40-46%,

[0010] Ag 10-20%,

[0011] Ni 8-15%;

[0012] The combined mass of Ag and Ni is 18-30%, and the combined mass of Pd and Ni is 40-50%.

[0013] The heat-treated palladium-silver-copper-nickel quaternary alloy rod has a hardness greater than 300 HV, a strength greater than 1000 MPa, and a resistivity less than 30.0 μΩ·cm.

[0014] This invention strictly controls the composition and dosage of alloy elements to obtain a high-performance palladium-silver-copper-nickel quaternary alloy for probes through reasonable element ratios and process optimization. Firstly, by controlling the palladium content to 30-38%, unlike the high palladium content of over 40% in traditional probe palladium alloys, raw material costs are significantly reduced, and the use of other expensive elements such as rhenium (Re) is avoided, further controlling raw material costs. Secondly, the alloy consists of only four elements: Pd, Cu, Ag, and Ni, reducing the difficulties in melting and large errors caused by the differences in melting points of the elements, minimizing compositional segregation and quality control challenges, and simplifying the heat treatment process.

[0015] This invention reduces the proportions of palladium and silver in the alloy by using nickel. The nickel in the alloy dissolves in the lattice of copper and palladium, forming a substitutional solid solution. This causes lattice distortion, increasing resistance to dislocation movement and thus improving the alloy's strength and hardness. During heat treatment, copper and palladium form fine intermetallic compound precipitates (such as PdCu-based precipitates). These nanoscale precipitates are uniformly distributed in the matrix, effectively hindering dislocation movement and providing additional strengthening effects, thereby further enhancing the alloy's mechanical properties.

[0016] This invention controls the total mass of Ag and Ni to 18-30%, ensuring a balance between the strengthening effect of nickel and the improvement of the processability and conductivity of silver; the total mass of Pd and Ni is controlled to 40-50%, ensuring a balance between the corrosion resistance of palladium and the strengthening effect of nickel.

[0017] This invention uses vacuum induction melting combined with directional solidification casting to obtain round bars of fixed size, which greatly improves the purity, compositional uniformity and microstructure of the alloy, eliminates the defects and segregation that may occur in traditional processes, and provides process support for obtaining stable and reliable high performance.

[0018] Preferably, the elemental composition of the palladium-silver-copper-nickel quaternary alloy rod, by mass percentage, is as follows:

[0019] Pd 32-36%,

[0020] Cu 41-45%,

[0021] Ag 10-15%,

[0022] Ni 8-12%;

[0023] The combined mass of Ag and Ni is 20-25%, and the combined mass of Pd and Ni is 42-46%.

[0024] The heat-treated palladium-silver-copper-nickel quaternary alloy rod has a hardness greater than 400 HV, a strength greater than 1200 MPa, and a resistivity less than 26.0 μΩ·cm.

[0025] Preferably, the elements are pre-melted by vacuum induction, melted by vacuum induction and directional solidification to form a palladium-silver-copper-nickel quaternary alloy.

[0026] Preferably, the diameter of the palladium-silver-copper-nickel quaternary alloy rod is 0.1-1.0 mm. The palladium-silver-copper-nickel quaternary alloy rod of the present invention can be manufactured according to the size requirements of the target probe.

[0027] In a second aspect of the present invention, a method for preparing the aforementioned high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes is also provided, comprising the following steps:

[0028] Step 1: The alloy raw materials are melted and cast in vacuum induction at a melting temperature of not less than 1200℃ to obtain alloy casting rods;

[0029] Step 2: Perform solution treatment on the alloy casting rod;

[0030] Step 3: Multi-pass cold rolling, followed by intermediate annealing, with the total cold rolling deformation below 90%;

[0031] Step 4: Multiple drawing passes, followed by intermediate solution heat treatment, with the total drawing deformation below 80%;

[0032] Step 5: Aging heat treatment at 350-550℃ to obtain the high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for the probe.

[0033] Preferably, in step 5, the aging heat treatment conditions include: heating to 350-550°C at a rate of 1-10°C / h, holding at that temperature for 30-150 minutes, and then slowly cooling to room temperature.

[0034] This invention, through the design of overall process steps and parameters at each stage, explores a suitable method for preparing palladium-silver-copper-nickel quaternary alloy into probe rods. It effectively provides high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rods by simplifying alloy composition and reducing the amount of precious metals used. Furthermore, solution treatment at 800-1000℃ allows Ni to fully dissolve into the matrix alloy. The combination of multi-pass cold rolling and intermediate annealing not only rapidly refines the deformation of the cast rod but also introduces high-density dislocations through cold rolling, generating a strong work hardening effect and increasing strength. The intermediate annealing then eliminates internal stress and restores plasticity; therefore, the annealing treatment between the two cold rolling cycles is crucial and necessary. The drawing process generates work hardening, improving the alloy's strength and hardness; aging heat treatment promotes the uniform and dispersed precipitation of nanoscale strengthening phases in the supersaturated solid solution. These fine second-phase particles effectively hinder dislocation movement, resulting in age-hardening effects. The above steps all help to ensure that the alloy rod has excellent comprehensive properties, including a hardness of over 300 HV, a strength of 1000 MPa, and a resistivity of less than 30.0 μΩ·cm.

[0035] Preferably, in step 1, the vacuum induction melting conditions include: a vacuum degree of 5 × 10⁻⁶. -3 For Pa below 20, the melting time is 20-60 minutes.

[0036] The alloy round bar is obtained by directional solidification casting, with a directional solidification traction speed of 0.2-0.25 mm / s.

[0037] Preferably, vacuum induction pre-melting is performed before step 1, including the following steps:

[0038] S1. Weigh palladium, silver, copper and nickel according to the mass percentage, mix them evenly, preheat and dry them and then fill them into a vacuum induction melting furnace.

[0039] S2. The vacuum degree of the vacuum induction melting furnace is 6.5×10⁻⁶. -2 Below Pa, heat to 1250-1350℃ at a rate of 10-20℃ / min, and hold for 5-15 minutes.

[0040] Pre-melting of palladium-silver-copper-nickel quaternary alloys before vacuum induction melting is a crucial step in improving the final alloy quality. Through a slow, high-temperature pre-melting process, the content of gases such as oxygen, hydrogen, and nitrogen in the alloy melt is significantly reduced. Furthermore, vacuum volatilization effectively removes unwanted low-melting-point impurities such as lead (Pb), bismuth (Bi), and tin (Sn) from the raw materials, improving alloy purity from the source. This also facilitates the pre-formation of a more homogeneous intermediate alloy (such as a silver-copper alloy), resolving the segregation problem that easily occurs among palladium, silver, copper, and nickel due to significant differences in melting point and density. It promotes the uniform distribution of high-melting-point and reactive elements, contributing to the subsequent production of alloy ingots with higher density, lower gas content, and superior processing performance.

[0041] Furthermore, the process of "pre-melting-cooling-melting-directional solidification" in this invention is very beneficial for balancing the comprehensive properties of the alloy: the first melting allows the alloy to initially fuse, and during the subsequent cooling and solidification process, the dissolved gases in the melt precipitate out due to the sharp decrease in solubility. When the alloy is heated and melted for the second time, these precipitated gases are more easily removed by the vacuum pump, thereby significantly improving the alloy density. The alloy rods obtained by directional solidification casting can then exhibit a smooth and flat surface and good microstructure uniformity.

[0042] Preferably, in step 2, the solution treatment conditions include: heating to 800-1000℃ at a rate of 15-30℃ / min, holding at that temperature for 1-3 hours, and then rapidly cooling by water quenching or ice-water quenching.

[0043] Solution treatment involves heating at a relatively high rate to above the alloy's recrystallization temperature. By controlling the heating rate and the solution temperature / time, the rapid growth of recrystallized grains at high temperatures is effectively suppressed, resulting in a finer and more uniform grain structure after solution treatment. This provides a superior initial microstructure for subsequent cold working and aging treatments.

[0044] Preferably, in step 3, the multiple cold rolling is performed along the axis of the alloy casting rod. Each time, the alloy casting rod is rotated around the axis by a certain angle before multiple cold rolling passes are performed. The deformation per pass is less than 15%, preferably less than 10%.

[0045] Intermediate annealing conditions include: heating to 700-750℃ at a rate of 10-30℃ / min, holding at that temperature for 10-15 minutes, and then slowly cooling to room temperature.

[0046] Preferably, the deformation per pass in the multi-pass drawing is 5-25%;

[0047] Intermediate solution heat treatment includes rapid solution heat treatment at 800-900℃ for 30-60 minutes followed by quenching.

[0048] After multiple drawing passes, straightening and cutting processes are performed to obtain quaternary alloy billets with diameters ranging from 0.3 to 1.0 mm.

[0049] Preferably, at least one of the solution treatment in step 2, the intermediate annealing treatment in step 3, the intermediate solution heat treatment in step 4, and the aging heat treatment in step 5 is carried out in a mixed reducing atmosphere of hydrogen and nitrogen, with a volume ratio of hydrogen to nitrogen of (1-5):(95-99).

[0050] Hydrogen (H2), as a strong reducing agent, can effectively remove oxides from metal surfaces, especially at high temperatures (above 1000℃), where it can reduce most metal oxides, ensuring the purity of alloy components and metallurgical quality. Nitrogen (N2), as a commonly used inert gas, dilutes hydrogen, reducing its explosion risk while maintaining the reducing environment. The hydrogen-nitrogen mixture is non-toxic and non-corrosive, friendly to equipment and the environment, and less expensive than pure hydrogen or helium. Therefore, considering reduction efficiency, safety, cost control, and process adaptability, the hydrogen-nitrogen mixed reducing atmosphere has significant advantages in alloy preparation processes, especially suitable for high-value-added alloys, such as the melting of precision palladium alloys for testing probes.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. Compared with traditional probe alloys with high palladium content (>40%) or containing rhenium, the quaternary alloy of the present invention significantly reduces the palladium content (below 38%) while avoiding the addition of expensive elements such as rhenium or other alloying elements through optimized composition design and preparation process. It achieves excellent comprehensive alloy performance on the basis of simple material usage, and solves the technical problem of balancing cost and performance of high-performance probe materials.

[0053] 2. The quaternary alloy of this invention reduces the proportion of palladium and silver in the alloy by using nickel. Nickel can dissolve in the lattice of copper and palladium to form a substitutional solid solution, leading to lattice distortion and increasing the resistance to dislocation movement, thereby improving the strength and hardness of the alloy. During heat treatment, copper and palladium can form fine intermetallic compound precipitates (such as PdCu-based precipitates). These nanoscale precipitates are uniformly distributed in the matrix, effectively hindering dislocation movement and providing additional strengthening effects, thereby further improving the mechanical properties of the alloy. In particular, this invention controls the sum of the mass of Ag and Ni to 18-30%, preferably 20-25%, to ensure a balance between the strengthening effect of nickel and the improvement of workability and conductivity of silver; the sum of the mass of Pd and Ni is controlled to 41-50%, preferably 45-46%, to ensure a balance between the corrosion resistance of palladium and the strengthening effect of nickel.

[0054] 3. This invention uses vacuum induction melting combined with a pre-melting process and a subsequent directional solidification casting technique to obtain round bars of fixed size, which is beneficial to improving the purity, compositional uniformity and microstructure of the alloy, eliminating defects and segregation that may occur in traditional processes, and providing process support for obtaining stable and reliable high performance. Attached Figure Description

[0055] The present invention will now be described with reference to the accompanying drawings.

[0056] Figure 1 This is a process flow diagram for preparing a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for the probe of this invention. Detailed Implementation

[0057] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0058] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0059] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0060] A high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes, wherein the elemental composition of the palladium-silver-copper-nickel quaternary alloy rod, by mass percentage, is as follows:

[0061] (1) Pd 30-38%, preferably 32-36%;

[0062] (2) Cu 40-46%, preferably 41-45%;

[0063] (3) Ag 10-20%, preferably 10-15%;

[0064] (4) Ni 8-15%, preferably 8-12%;

[0065] The total mass of Ag and Ni is 18-30%, preferably 20-25%.

[0066] The total mass of Pd and Ni is 40-50%, preferably 42-46%;

[0067] The heat-treated palladium-silver-copper-nickel quaternary alloy rod has a hardness greater than 300 HV, preferably greater than 350 HV, more preferably greater than 400 HV; a strength greater than 1000 MPa, preferably greater than 1200 MPa, more preferably greater than 1400 MPa; and a resistivity less than 30.0 μΩ·cm, preferably less than 26.0 μΩ·cm.

[0068] The specific forms of raw materials can be palladium flakes (Pd≥99.95%), electrolytic copper granules (Cu≥99.99%), silver granules (Ag≥99.99%), and nickel granules (Ni≥99.95%).

[0069] See appendix Figure 1 The preparation method of the above-mentioned probe using a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod specifically includes:

[0070] Step 1: The alloy raw materials are melted at a melting temperature of not less than 1200℃, and alloy rods are obtained by vacuum induction melting and directional solidification casting.

[0071] 1.1 Vacuum induction melting: vacuum degree of 5×10 -3 For Pa below 20-60 min (including total melting and holding time), alloy casting rods are obtained.

[0072] Step 2: In a mixed reducing atmosphere of hydrogen and nitrogen, the alloy casting rod is solution treated and then rapidly cooled. The solution treatment is carried out by heating to 800-1000℃ at a rate of 15-30℃ / min, holding for 1-3 hours, and then rapidly cooling by water quenching or ice-water quenching.

[0073] Step 3: The multiple cold rolling is performed along the axis of the alloy casting. Each time, the alloy casting is rotated around the axis by a certain angle before multiple cold rolling passes are performed, for example, 5-25 cold rolling passes, with a deformation per pass of less than 15%, preferably less than 10%, and more preferably less than 5%. For example, the solution-treated alloy casting is cold rolled twice along the axial direction, with a 90° rotation between the two cold rolling passes. Each cold rolling pass consists of 15 cold rolling passes, with a deformation per pass of approximately 5%, and a total cold rolling deformation of approximately 78%. Furthermore, when increasing the cold rolling... During the rolling process, the preferred rotation angle is to ensure uniform rolling of the alloy casting rod along the circumferential direction, i.e., rotating sequentially 360° / n, where n≥3. For example, for 3 cold rolling cycles, a sequential rotation of approximately 120° can be selected, and for 6 cold rolling cycles, a sequential rotation of 60° can be selected. Intermediate annealing is then performed in a mixed reducing atmosphere of hydrogen and nitrogen. The intermediate annealing conditions include: heating to 700-750°C at a rate of 10-30°C / min, holding at that temperature for 10-15min, and then slowly cooling to room temperature.

[0074] Step 4: The drawn round bar is obtained by multiple drawing passes, with a deformation of 5-25% per pass and a total deformation of less than 80%; between multiple drawing passes, an intermediate solution heat treatment is carried out in a mixed reducing atmosphere of hydrogen and nitrogen. The intermediate solution heat treatment conditions include: rapid solution heat treatment at 800-900℃ for 30-60 minutes followed by quenching.

[0075] After multiple drawing passes, straightening and cutting processes are carried out to obtain quaternary alloy billet;

[0076] Step 5: In a mixed reducing atmosphere of hydrogen and nitrogen, perform aging heat treatment at 350-550℃ to obtain the high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for the probe with a diameter of 0.3-1.0 mm. The aging heat treatment conditions include: heating to 350-550℃ at a rate of 1-10℃ / h, holding at that temperature for 30-150 min, and then slowly cooling to room temperature.

[0077] In the mixed reducing atmosphere of hydrogen and nitrogen, the volume ratio of hydrogen to nitrogen is (1-5):(95-99).

[0078] Based on the above composition ratio and manufacturing method, palladium-silver-copper-nickel quaternary alloy rods with various compositions can be prepared through the following examples and comparative examples. Samples of each palladium-silver-copper-nickel quaternary alloy rod are prepared for evaluation tests on hardness, resistivity, bending resistance and mechanical properties. Multiple samples of each palladium alloy material are prepared for parallel testing to obtain the average value and deviation of each evaluation test.

[0079] Example 1

[0080] The palladium-silver-copper-nickel quaternary alloy rod of Example 1, by mass, has a target composition of Pd. 38 Ag9Cu 43 Ni10 It is prepared by the following method, specifically including the following steps:

[0081] Preparation of materials: Weigh out 38.0% palladium flakes (Pd≥99.95%), 43.0% electrolytic copper granules (Cu≥99.99%), 9.0% silver granules (Ag≥99.99%), and 10.0% nickel granules (Ni≥99.95%) according to the target composition. Each raw material is ultrasonically cleaned with acetone for 15 min and vacuum dried at 80℃ for 2 h.

[0082] Step 1: Vacuum Induction Melting

[0083] Vacuum induction melting: Mix all raw materials evenly, place them in a boron carbide crucible, and put it in a medium-frequency vacuum induction melting furnace. Evacuate the furnace to a vacuum level of 1×10⁻⁶. -3 Pa, then a protective gas mixture of argon and hydrogen (volume ratio 9:1) is introduced to maintain a pressure of 0.05 MPa. The temperature is increased to 1300℃±10℃ at a rate of 25℃ / min, during which 50Hz electromagnetic stirring is applied. The melting process lasts for 5 min and is held at that temperature for 45 min. During this process, directional solidification is used to cast a round bar of fixed size. The directional solidification traction speed is 0.2-0.25 mm / s.

[0084] Step 2: Solution treatment of the alloy casting in a mixed reducing atmosphere of hydrogen and nitrogen (volume ratio 4:96) includes: heating to 950±10℃ at a rate of 20℃ / min, holding for 1h, and rapid cooling by water quenching.

[0085] Step 3: The solution-treated alloy rod is cold-rolled twice along the axial direction, rotating 90° between the two cold rolling operations. Each cold rolling operation consists of 15 passes, with a deformation of approximately 5% per pass and a total deformation of approximately 78%. Between the two cold rolling operations, an intermediate annealing treatment is performed in a mixed reducing atmosphere of hydrogen and nitrogen (volume ratio 4:96). The intermediate annealing conditions include heating to 720±5℃ at a rate of 20℃ / min, holding at that temperature for 15min, and then slowly cooling to room temperature.

[0086] Step 4: A drawn round bar is obtained through four drawing passes, with a pass deformation of 15-20% and a total drawing deformation of less than 60%. Specifically, this includes:

[0087] First pass: 2.0mm to 1.6mm (single deformation amount of about 20.0%), after drawing, hold at 880℃ for 30 minutes and then water quench;

[0088] Second pass: 1.6mm to 1.28mm (single deformation amount approximately 20.0%), intermediate solution treatment under the same conditions;

[0089] Third pass: 1.28mm to 1.0mm (single deformation amount approximately 20.0%), intermediate solution treatment under the same conditions;

[0090] 4th pass: 1.0mm to 0.85mm (single pass deformation of approximately 15.0%).

[0091] After multiple drawing passes, straightening and cutting processes are performed to obtain quaternary alloy billets with a diameter of approximately 0.8 mm.

[0092] Step 5: Aging heat treatment was performed in a mixed reducing atmosphere of hydrogen and nitrogen at a pressure of about 1.0 MPa (volume ratio 4:96), with the temperature increased to 400±5℃ at a rate of 6℃ / min and held for 60 min to obtain the high-hardness and high-strength palladium-silver-copper-nickel quaternary alloy rod sample for probe of Example 1.

[0093] Example 2

[0094] The raw material composition of the palladium-silver-copper-nickel quaternary alloy rod in Example 2 differs from that in Example 1. By mass, the target component in Example 2 is Pd. 38 Ag 10 Cu 44 Ni8 is prepared through the following steps:

[0095] Weigh out 38.0% palladium flakes (Pd≥99.95%), 44.0% electrolytic copper granules (Cu≥99.99%), 10.0% silver granules (Ag≥99.99%), and 8.0% nickel granules (Ni≥99.95%) according to the target composition. Each raw material is ultrasonically cleaned with acetone for 15 min and vacuum dried at 80℃ for 2 h.

[0096] Steps 1 to 5 are the same as in Example 1, resulting in a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for the probe of Example 2 with a diameter of approximately 0.8 mm.

[0097] Example 3

[0098] The raw material composition of the palladium-silver-copper-nickel quaternary alloy rod in Example 3 differs from that in Example 1. By mass, the target component in Example 2 is Pd. 38 Ag 10 Cu 42 Ni 10 Prepare materials through the following steps:

[0099] Weigh out 38.0% palladium flakes (Pd≥99.95%), 42.0% electrolytic copper granules (Cu≥99.99%), 10.0% silver granules (Ag≥99.99%), and 10.0% nickel granules (Ni≥99.95%) according to the target composition. Each raw material is ultrasonically cleaned with acetone for 15 min and vacuum dried at 80℃ for 2 h.

[0100] Steps 1 to 5 are the same as in Example 1, resulting in a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for the probe of Example 3 with a diameter of approximately 0.8 mm.

[0101] Example 4

[0102] The raw material composition of the palladium-silver-copper-nickel quaternary alloy rod in Example 4 differs from that in Example 1. By mass, the target component in Example 4 is Pd. 38 Ag 15 Cu 40 Ni7 is prepared through the following steps:

[0103] Weigh out 38.0% of palladium flakes (Pd≥99.95%), 40.0% of electrolytic copper granules (Cu≥99.99%), 15.0% of silver granules (Ag≥99.99%), and 7.0% of nickel granules (Ni≥99.95%) according to the target composition. Each raw material is ultrasonically cleaned with acetone for 15 min and vacuum dried at 80℃ for 2 h.

[0104] Steps 1 to 5 are the same as in Example 1, resulting in a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for the probe of Example 4 with a diameter of approximately 0.8 mm.

[0105] Example 5

[0106] The raw material composition of the palladium-silver-copper-nickel quaternary alloy rod in Example 5 differs from that in Example 1. By mass, the target component in Example 5 is Pd. 30 Ag9Cu 46 Ni 15 Prepare materials through the following steps:

[0107] Weigh out 30.0% of palladium flakes (Pd≥99.95%), 46.0% of electrolytic copper granules (Cu≥99.99%), 9.0% of silver granules (Ag≥99.99%), and 15.0% of nickel granules (Ni≥99.95%) according to the target composition. Each raw material is ultrasonically cleaned with acetone for 15 min and vacuum dried at 80℃ for 2 h.

[0108] Steps 1 to 5 are the same as in Example 1, resulting in a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for the probe of Example 5 with a diameter of approximately 0.8 mm.

[0109] Example 6

[0110] The raw material composition of the palladium-silver-copper-nickel quaternary alloy rod in Example 6 differs from that in Example 1. By mass, the target component in Example 6 is Pd. 36 Ag 11 Cu 43 Ni 10 Prepare materials through the following steps:

[0111] Weigh out 36.0% of palladium flakes (Pd≥99.95%), 43.0% of electrolytic copper granules (Cu≥99.99%), 11.0% of silver granules (Ag≥99.99%), and 10.0% of nickel granules (Ni≥99.95%) according to the target composition. Each raw material is ultrasonically cleaned with acetone for 15 min and vacuum dried at 80℃ for 2 h.

[0112] Steps 1 to 5 are the same as in Example 1, resulting in a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for probes of Example 6 with a diameter of approximately 0.8 mm.

[0113] Comparative Examples 1-4

[0114] The difference between Comparative Examples 1-4 and Examples 1-6 lies in the different elemental proportions of the alloy raw materials, as shown in Table 1.

[0115] Table 1. Elemental proportions (wt%) of Examples 1-6 and Comparative Examples 1-4

[0116]

[0117] Example 7

[0118] Example 7: Palladium-silver-copper-nickel quaternary alloy rod Pd 38 Ag 10 Cu 44 The difference between Ni8 and Example 2 lies in step 4 of the preparation method, where a drawn round bar is obtained through 5 drawing passes, with the deformation per pass gradually decreasing from approximately 25% to approximately 5%, and the total drawing deformation being less than 60%. Specifically, this includes:

[0119] First pass: 2.0mm to 1.5mm (single deformation amount approximately 25.0%), after drawing, hold at 880℃ for 30 minutes and then water quench;

[0120] Second pass: 1.5mm to 1.2mm (single deformation amount approximately 20.0%), intermediate solution treatment under the same conditions;

[0121] Third pass: 1.2mm to 1.0mm (single deformation amount approximately 15.0%), intermediate solution treatment under the same conditions;

[0122] 4th pass: 1.0mm to 0.9mm (single deformation amount approximately 10.0%), intermediate solution treatment under the same conditions;

[0123] 5th pass: 0.9mm to 0.85mm (single pass deformation of approximately 5.0%).

[0124] After multiple drawing passes, straightening and cutting processes are performed to obtain quaternary alloy billets with a diameter of approximately 0.8 mm.

[0125] The other steps are the same as in Example 2, and the high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for probe of Example 7 is obtained.

[0126] Example 8

[0127] Example 8: Palladium-silver-copper-nickel quaternary alloy rod Pd 38 Ag 10 Cu 44 The difference between Ni8 and Example 2 is that in step 3, the alloy rod after solution treatment is cold rolled three times along the axial direction, with a sequential rotation of about 120° between the three cold rolls. Each cold roll consists of 13 passes, with a deformation of about 4% per pass and a total deformation of about 78%. Between the three cold rolls, an intermediate annealing treatment is performed in a mixed reducing atmosphere of hydrogen and nitrogen (volume ratio 4:96). The intermediate annealing conditions include heating to 720±5°C at a rate of 20°C / min, holding at that temperature for 15 min, and then slowly cooling to room temperature.

[0128] The other steps are the same as in Example 2, and the high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for probes in Example 8 is obtained.

[0129] Example 9

[0130] Example 9: Palladium-silver-copper-nickel quaternary alloy rod Pd 38 Ag 10 Cu 44 The difference between Ni8 and Example 2 is that, before the melting in step 1, a vacuum induction pre-melting process is performed, including the following steps:

[0131] S1. Weigh palladium, silver, copper and nickel according to mass percentage, mix them evenly, preheat and dry them in vacuum at 150℃, and then fill them into a vacuum induction melting furnace.

[0132] S2, The vacuum degree of the vacuum induction melting furnace is 5×10 -3 Pa is heated to 1300℃ at a rate of 15℃ / min and held for 10min.

[0133] The pre-melted alloy is then subjected to vacuum induction melting and directional solidification casting to obtain alloy casting rods.

[0134] The other steps are the same as in Example 2, and a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod sample for probes of Example 9 with a diameter of about 0.8 mm is obtained.

[0135] Test methods and results

[0136] The samples obtained from Examples 1-9 and Comparative Examples 1-4 were subjected to performance tests. These tests were conducted on samples before aging heat treatment (only step 4 was completed, 5 samples were selected for each) and after aging treatment (step 5 was completed, 5 samples were selected for each). The test results are shown in Table 2.

[0137] (1) Hardness test: Vickers hardness tester was used. The load was set to 200gf and the indentation time was set to 10 seconds.

[0138] (2) Resistivity test: The resistance is measured using a resistance meter, and the resistivity is calculated from the cross-sectional area and length of the sample.

[0139] (3) Bending resistance test: One end of the alloy wire (0.8 mm in diameter) is fixed with a clamp and bent at a 90° angle, then bent back to a straight state. This process of bending 90° and returning to a straight state is repeated alternately, and the number of bends until breakage is counted for evaluation. This bending resistance test is also performed on the wire before and after aging heat treatment.

[0140] (4) Mechanical performance testing shall be conducted in accordance with standard GB / T 228.1-2021.

[0141] Table 2 Test results of Examples 1-9 and Comparative Examples 1-4

[0142]

[0143] The test results show that, after heat treatment, the palladium-silver-copper-nickel quaternary alloy rod of the embodiment has a hardness greater than 300 HV, preferably greater than 350 HV, and more preferably greater than 400 HV; a tensile strength greater than 1000 MPa, preferably greater than 1200 MPa, and more preferably greater than 1400 MPa; a resistivity less than 30.0 μΩ·cm, preferably less than 26.0 μΩ·cm, and more preferably less than 25.0 μΩ·cm; more than 5 90° bends; and an elongation of less than 10%, preferably 6-8%. The comparative example, however, cannot simultaneously meet the aforementioned comprehensive performance requirements.

[0144] A comparison of the processes in Examples 7-9 and Example 2 shows that, with essentially the same alloy raw materials, the multiple drawing processes, multiple cold rolling processes, and pre-melting steps in the preparation method have a certain impact on the overall performance of the alloy product. Therefore, by adjusting the alloy element composition and selecting the process conditions of the preparation method, the individual or combined properties of the palladium-silver-copper-nickel quaternary alloy can be controlled, thereby reducing costs while meeting the actual performance requirements of high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rods for probes.

[0145] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the invention is intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the invention and its equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes, characterized in that, The elemental composition of the palladium-silver-copper-nickel quaternary alloy rod, by mass percentage, is as follows: Pd 30-38%, Cu 40-46%, Ag 9-20%, Ni 7-15%; The combined mass of Ag and Ni is 18-30%, and the combined mass of Pd and Ni is 41-50%. The heat-treated palladium-silver-copper-nickel quaternary alloy rod has a hardness greater than 300 HV, a strength greater than 1000 MPa, and a resistivity less than 30.0 μΩ·cm. The probe is prepared using a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod through the following steps: Step 1: The alloy raw materials are melted at a melting temperature of not less than 1200℃, and alloy rods are obtained by vacuum induction melting and directional solidification casting. Step 2: Solution treatment of alloy casting rods: Heat to 800-1000℃ at a rate of 15-30℃ / min, hold for 1-3 hours, and then cool rapidly by water quenching or ice-water quenching. Step 3: Multiple cold rolling processes followed by intermediate annealing, with the total cold rolling deformation below 90%; the multiple cold rolling processes are carried out along the axis of the alloy casting rod, with each pass involving multiple cold rolling cycles after rotating the alloy casting rod around the axis by a certain angle, and the deformation per pass below 15%; the intermediate annealing conditions include: heating to 700-750℃ at a rate of 10-30℃ / min, holding at that temperature for 10-15min, and then slowly cooling to room temperature; Step 4: Multiple drawing passes with intermediate solution heat treatment, the total deformation of the drawing is less than 80%; the deformation of each pass in the multiple drawing passes is 5-25%, and the deformation gradually decreases from the first pass to the last; the intermediate solution heat treatment includes solution heat treatment at 800-900℃ for 30-60 minutes followed by rapid cooling. Step 5: Aging heat treatment at 350-550℃ to obtain the high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for the probe.

2. The high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes as described in claim 1, characterized in that, The elemental composition of the palladium-silver-copper-nickel quaternary alloy rod, by mass percentage, is as follows: Pd 32-36%, Cu 41-45%, Ag 10-15%, Ni 8-12%; The combined mass of Ag and Ni is 20-25%, and the combined mass of Pd and Ni is 45-46%. The heat-treated palladium-silver-copper-nickel quaternary alloy rod has a hardness greater than 400 HV, a strength greater than 1200 MPa, and a resistivity less than 26.0 μΩ·cm.

3. The high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for probes as described in claim 1 or 2, characterized in that, The elements are pre-melted under vacuum induction, melted under vacuum induction and directional solidification to form a palladium-silver-copper-nickel quaternary alloy.

4. A method for preparing a high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for a probe as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: The alloy raw materials are melted at a melting temperature of not less than 1200℃, and alloy rods are obtained by vacuum induction melting and directional solidification casting. Step 2: Solution treatment of alloy casting rods: Heat to 800-1000℃ at a rate of 15-30℃ / min, hold for 1-3 hours, and then cool rapidly by water quenching or ice-water quenching. Step 3: Multiple cold rolling processes followed by intermediate annealing, with the total cold rolling deformation below 90%; the multiple cold rolling processes are carried out along the axis of the alloy casting rod, with each pass involving multiple cold rolling cycles after rotating the alloy casting rod around the axis by a certain angle, and the deformation per pass below 15%; the intermediate annealing conditions include: heating to 700-750℃ at a rate of 10-30℃ / min, holding at that temperature for 10-15min, and then slowly cooling to room temperature; Step 4: Multiple drawing passes with intermediate solution heat treatment, the total deformation of the drawing is less than 80%; the deformation of each pass in the multiple drawing passes is 5-25%, and the deformation gradually decreases from the first pass to the last; the intermediate solution heat treatment includes solution heat treatment at 800-900℃ for 30-60 minutes followed by rapid cooling. Step 5: Aging heat treatment at 350-550℃ to obtain the high-hardness, high-strength palladium-silver-copper-nickel quaternary alloy rod for the probe.

5. The preparation method according to claim 4, characterized in that, In step 1, the vacuum induction melting conditions include: a vacuum degree of 5 × 10⁻⁶. -3 For Pa below 20, the melting time is 20-60 minutes.

6. The preparation method according to claim 4, characterized in that, In step 1, the alloy round bar is obtained by directional solidification casting, and the directional solidification traction speed is 0.2-0.25 mm / s.

7. The preparation method according to claim 5 or 6, characterized in that, Prior to step 1, vacuum induction pre-melting is performed, including the following steps: S1. Weigh palladium, silver, copper and nickel by mass percentage, preheat and dry them and then fill them into a vacuum induction melting furnace. S2. The vacuum degree of the vacuum induction melting furnace is 6.5×10⁻⁶. -2 Below Pa, heat to 1250-1350℃ at a rate of 10-20℃ / min, and hold for 5-15 minutes.

8. The preparation method according to claim 4, characterized in that, After multiple drawing passes, straightening and cutting processes are performed to obtain quaternary alloy billets with diameters ranging from 0.3 to 1.0 mm.

9. The preparation method according to claim 4, characterized in that, At least one of the following steps—solution treatment in step 2, intermediate annealing in step 3, intermediate solution heat treatment in step 4, and aging heat treatment in step 5—is carried out in a mixed reducing atmosphere of hydrogen and nitrogen, with a volume ratio of hydrogen to nitrogen of (1-5):(95-99).

Images