High-strength high-conductivity copper alloy composition and preparation process optimization

Title: High-strength high-conductivity copper alloy composition and preparation process optimization
　　Author: Peng India
　　Degree-granting units: Nanchang University
　　Keywords: high strength and high conductivity copper alloy;; composition;; cold deformation;; heat;; vacuum induction melting
　　Summary:
　　With the development of the electronics industry to meet the ultra-large scale integrated circuit lead frame material of the desired performance requirements: tensile strength σb> 600MPa, micro-hardness HV> 180, conductivity> 80% IACS, softening temperature> 500 ℃, the researchers From the strain hardening, solid solution strengthening, precipitation Magnetic lifter strengthening, fine grain strengthening, composite strengthening other aspects of development of high strength and high conductivity copper-based materials. In order to obtain the desired performance, the establishment of a China's own high strength and high conductivity copper alloy material system is imperative.
　　In this paper, high strength and high conductivity copper alloy composition design, smelting process and heat treatment system on the microstructure and properties of the relationship between aspects of the system studied, and on this basis to achieve the optimization of alloy composition and process, and ultimately be good overall performance of the alloy . The results are as follows:
　　(1) liquid copper alloy solidification using a larger cooling rate, alloy composition segregation can be reduced to obtain more uniform microstructure and properties. Before pouring the liquid alloy to reduce the temperature after the live casting, casting speed should be slow, in the whole process a little faster after using the first slow and then slow down the speed of the final casting, can be more uniform texture, more compact and lighter shrinkage of copper alloy casting rod.
　　(2) study the composition of the alloy: by adding rare earth rare-earth Y Nd ratio can be higher hardness, more stable performance and more uniform tissue, add effects to play better; precipitation strengthened alloy elements added to the amount of Cr should be appropriate, the adding amount of 0.8wt% when you can get a good comprehensive mechanical and electrical performance; Zr elements added, can significantly improve the alloy microstructure refinement of grain boundaries, reducing the Cu-Cr eutectic generation to improve the hardness of the alloy and improve the thermal stability of the alloy, the added amount can be obtained at 0.2wt% hardness and good conductivity match the overall performance; sum get two Jiaoyou performance of the alloy composition ratio, One is not to join the elements Zr alloy, the hardness is slightly lower, but the higher conductivity of Cu-0.8Cr-0.05Y (wt%) alloy composition, the other is adding Zr element, the higher hardness values, http://www.999magnet.com/products/131-magnetic-lifter but slightly lower conductivity The Cu-0.8Cr-0.2Zr-0.05Y (wt%) alloy composition.
　　(3) alloy after 70% deformation, deformation is inadequate; to 90% when the deformation, the grain was being stretched, can produce more defects such as vacancies and dislocations, as the solution to provide more precipitation atomic channel is conducive to the precipitation of the latter part of aging, the strain hardening effect is remarkable.
　　(4) of the solid solution alloy heat treatment process, aging temperature and aging time on the sample and the performance of the organization, got the better preparation process: Cu-0.8Cr-0.05Y alloy with 90% deformation +480 ℃ × 12min aging treatment, you can get hardness 176HV, tensile strength of 540MPa, conductive rate of 84.8% IACS, softening temperature of 525 ± 5 ℃ of good overall performance; Cu-0.8Cr-0.2Zr-0.05Y alloy with 90% deformation +500 ℃ × 60min aging, the hardness of 194HV, tensile strength of 552MPa, the conductivity of up to 83.3% IACS, softening temperature up to 580 ± 5 ℃ of good performance.
　　Degree Year: 2010