Study On Structure And Properties Of Cu-35Pt-(5Ir,10Ir) Alloy

The binary phase diagram of the copper-platinum alloy shows that the Cu-Pt alloy at the copper-rich end will generate an ordered phase of Cu₃Pt when annealed in a wide temperature range below 645°C.The formation of ordered phases will change the structure of the alloy,thereby affecting the properties of the alloy.However,the effect of the formation of ordered phases of Cu₃Pt on the structure and properties of copper-platinum alloys and the microscopic mechanism behind it have been rarely reported so far.Therefore,this study focuses on the effect of the formation of Cu₃Pt ordered phase on the structure and properties of Cu-35Pt alloy and its mechanism under certain processing and heat treatment processes.In addition,the high-melting and high-strength precious metals Ir and Pt can be infinitely dissolved in solid solution,and Ir also has a high solubility in Cu.Therefore,this paper further studied the influence of the addition of Ir on the structure and properties of Cu-35Pt alloy.In this paper,Cu-35Pt,Cu-35Pt-5Ir and Cu-35Pt-10Ir are designed.It is prepared by high-vacuum arc melting and induction melting,rolling and drawing,and then studied by transmission electron microscope,scanning electron microscope,X-ray diffraction analyzer,optical microscope and microhardness,tensile properties,electrical conductivity,etc.The effect of mechanical heat treatment on the structure and properties of Cu-35Pt-(5Ir,10Ir)alloy.The results of the study are as follows:(1)Cu-35Pt-(5Ir,10Ir)alloy has significant solid solution strengthening and work hardening.The microhardness of the solid solution alloy reaches 108.6HV,182.2HV and 207.4HV,respectively;the microhardness of the quenched alloy reaches 247HV,247HV after 90%deformation.270.4HV and 288HV,after adding Ir,the solid solution strengthening effect is greatly improved.The three alloys have significant low temperature annealing and age hardening behavior.The 90%deformed Cu-35Pt-(5Ir,10Ir)three alloys are respectively annealed and aging treated at 250?and 400?,and the microhardness reaches the maximum,respectively.They are 282 HV,318.6HV and331.8HV,compared with the processed state,the alloy microhardness has been significantly improved.The addition of Ir increases the optimal hardening aging temperature of the alloy from 250°C for Cu-35Pt alloy to 400°C for Cu-35Pt-5Ir and Cu-35Pt-10Ir alloys.(2)After cold-rolling to 90%deformed processing state Cu-35Pt-(5Ir,10Ir)three alloys after low temperature aging treatment,the strength and toughness are significantly improved at the same time.And the best aging strengthening effect is obtained after aging treatment at 250?and 400?.Its tensile strength is 683MPa,980MPa,1004MPa,respectively,which are 12%,32%and 24%higher than the processed state,and the elongation is 2?4 times that of the processed state,after aging at 500?,its strength is not lower than The processing state,but the elongation has been further greatly improved,the addition of Ir significantly improves the aging strengthening effect of the Cu-35Pt alloy.(3)Alloys as the annealing temperature was increased from 200°C to 800°C,the electrical conductivity of Cu-35Pt-(5Ir,10Ir)three-component alloys has increased significantly.Among them,Cu-35Pt,Cu-35Pt-5Ir and Cu-35Pt-10Ir alloys,respectively When the strength and hardness are the highest after annealing at 250?and 400?,their electrical conductivity is 4.0×10~6S/m,4.30×10~6S/m and 4.20×10~6S/m,respectively.The electrical conductivity of the three alloys reached the maximum after annealing at 500?,which were 5.40×10~6S/m,4.54×10~6S/m and 4.53×10~6S/m,respectively.The addition of Ir has little effect on the electrical conductivity,and after the aging temperature treatment at which the alloy obtains the highest strengthening effect,its electrical conductivity is higher than that of the Cu-35Pt alloy.(4)During the low temperature aging process of Cu-35Pt-(5Ir,10Ir)alloy,a nano-scale Cu3Pt ordered phase is formed in the disordered solid solution matrix of the alloy,which is dispersed in the alloy matrix to form a long-range ordered superlattice structure.This is the fundamental reason why the performance of the alloy has been significantly improved during the low-temperature aging process.In summary,Cu-35Pt-(5Ir,10Ir)alloy has excellent solid solution strengthening and ordered phase precipitation strengthening effects,and the processed alloy can obtain high strength and toughness after low temperature aging treatment.Cu-35Pt-5Ir and Cu-35Pt-10Ir alloys have more excellent comprehensive properties and have good potential application value in the field of electrical contact materials.