Data-driven Design And Preparation Process Of High-Performance Multicomponent Complex Copper Alloys

High-performance copper alloys for integrated circuit leadframes are one of the key materials for the electronic information industry,and the rapid development of the chip industry has put forward higher requirements for the comprehensive performance of leadframe copper alloys.Traditional trial-and-error based design methods for high performance copper alloys have long development cycles and high costs.The rapid development of data-driven machine learning methods for new material discovery in recent years provides an important opportunity to promote the efficient development of new high-performance copper alloys.In this thesis a property-oriented high performance copper alloy composition design system is developed by using data-driven machine learning modeling method,which realizes the efficient reverse design of high-performance copper alloy and breaks through the problem of designing alloy composition according to properties requirements.The influence of preparation process on the microstructure and properties of the designed typical alloy was studied,which laid a foundation for the engineering application of the alloy.The main results are as follows:A high performance copper alloy composition reverse design system(machine learning design system,MLDS)for properties requirements is developed,which can realize the composition design according to the properties requirements within ultimate tensile strength of 600?950MPa and electrical conductivity of 40?55%IACS.Cu-3.0Ni-0.6Si-0.16Zn-0.15Cr-0.03P alloy(abbreviated as CuNiSiZnCrP alloy)was designed by MLDS with tensile strength of 800MPa and conductivity of 50%IACS as typical design objectives.The experimental results show that the error between the measured properties and the design target is less than 5%.In order to investigate the role of Zn,Cr and P in the designed CuNiSiZnCrP alloy,by increasing Zn,Cr and P on the basis of Cu-Ni-Si ternary alloy,the microstructure and properties of four alloys after hot rolling,solid solution,cold rolling and aging treatment were studied.The results show that the addition of Zn,Cr and P increases the dislocation density of Cu-Ni-Si alloy after cold rolling.After peak aging,the size of precipitates was uniform and dispersed,and the peak hardness,tensile strength,electrical conductivity,anti-aging and high temperature softening properties were improved.The results can provide the experimental basis for optimizing the alloy preparation parameters.The hot deformation behavior of CuNiSiZnCrP alloy was studied by hot compression simulation experiment,and the constitutive equation was established according to the true stress-true strain curve of the alloy during hot compression,the suitable hot working temperature is 800?900?,and the strain rate is 0.01?0.5s-1.The initial recrystallization temperature and the initial precipitation temperature of the second phase of the cold rolled alloy with different deformation were studied.The peak tensile strength of 85%cold rolled alloy was 776±12MPa and its conductivity was 47.5±0.9%IACS after aging at 450?@60min.In the early stage of aging at 450?,?-Ni2Si with regular triangular shape precipitates in the matrix and remains coherent with the copper matrix near the dislocation cell wall,the precipitates are semi-coherent to the matrix,spherical in shape and oriented to the copper matrix:(1-11),//(042)?,[-110]m//[-32-4]?.On the basis of single-stage aging process,two-stage cold-rolling-aging process and pre-aging+two-stage cold-rolling-aging process for CuNiSiZnCrP alloy were developed to improve its tensile strength and electrical conductivity.After two-stage cold rolling-aging treatment(85%cold-rolling at 450?@60min+95%cold-rolling 450?@30min),the tensile strength and electrical conductivity of the alloy were 856 ±26 MPa and 52.4±0.8%IACS,respectively.After pre-aging+two-stage cold-rolling-aging treatment(450?@90min+85%cold-rolling+450?@60min+95%cold-rolling+450?@10min),the tensile strength and electrical conductivity of the alloy were 905±11MPa and 52.5±0.2%IACS,respectively.A large amount of nano ?-Ni2Si precipitates were observed in the two aging processes,which resulted in more dispersion of cold-rolled dislocations and further precipitation of solute atoms.There are two kinds of ?-Ni2Si phases with uniform size distribution in the alloy matrix,which cooperatively strengthen the alloy matrix.