Copper Alloys Diffusion Mobility Database Establishment And Its Application In Structural Evolution And Properties Prediction

Copper and copper alloys are indispensable materials for economic and technological development.How to design copper alloys with excellent strength and electrical conductivity has always been an urgent scientific and technical problem to be solved in this field.The strength and electrical conductivity of copper alloys are determined by the microstructure of the alloy,whereas the formation of the microstructure is affected by solidification and heat treatment conditions.Due to the lack of reliable kinetic parameters,the microstructure simulation and performance prediction of copper alloys during solidification and hot processing are limited.Therefore,this work intends to explore the application of Materials Genome Initiative in the research of high-performance copper alloys.An accurate diffusion mobility database of copper alloys is established by integrating key experiments and various calculation methods.The various phenomena of diffusion control during solidification and heat treatment of copper alloys were simulated dynamically by coupling the thermodynamic and kinetic database.The conductivity and strength of copper alloy were predicted by using the simulated microstructure parameters,their reliability is verified by experimental data.The main innovation achievements of this work are as follows:(1)Based on critical literature evaluation,first-principles calculations,empirical equations,and modified Sutherland equations,the self-diffusion mobilities of 28 alloy elements in fcc phase and liquid phase and the impurity atomic mobilities of 378 sub-binary systems were comprehensively evaluated and calculated.Eight binary systems incompatible with the current mobility database were re-evaluated.The atomic mobility parameters of 8 binary systems were optimized based on the diffusion experiment data.The first comprehensive diffusion mobiity database of binary copper alloys was established.(2)The compositional profiles of Cu-Co-Mn,Cu-Mn-Si,Co-Ni-Si and Mn-Ni-Si diffusion couples and the compositional distance distribution surface of Co-Mn-Ni diffusion triple were experimentally measured.CALTPP(CALculation of Themo Physical Properties)was used to calculate the interdiffuvities and optimize the atomic mobility parameters.Combined with literature evaluation and experimental measurement,an accurate database of fcc phase diffusion mobility of CuCo-Mn-Ni-Si system were established.(3)Based on the established diffusion mobility database in this work and the copper alloys thermodynamics database of our group,CALTPP was used to simulate the diffusion behavior of a series of alloys in fcc phase and liquid phase.The simulation results were consistent with the experimental results,which verified the accuracy of the copper alloy diffusion mobility database.The solidification paths of the sub-system in Cu-Co-Mn-Ni-Si alloy were predicted by DICTRA and the growth of precipitated particles in Cu-X(X=Co,Fe and Mn)binary alloys and CuNi-Mn,Cu-Ni-Si and Cu-Ni-Co-Si multicomponent alloys during aging were simulated by TC-PRISMA.The importance of diffusion mobility parameters for simulating and predicting the microstructure changes of alloys during hot processing were demonstrated.(4)The homogenization time of the Cu-2.78Ni-1.39Co-1.08Si(wt.%)alloy at 1213 K was model-predicted.The prediction results were verified experimentally.According to the change of conductivity with aging time,the transformation kinetics Avrami equation at different aging temperatures was established.The experimental results showed that the hardness of Cu-2.78Ni-1.39Co-1.08Si(wt.%)alloy reached the highest 332.3 HV and the corresponding electrical conductivity was 37.9% IACS after aging at 773 K for 1 h.After aging at 723 K for 4 h,the comprehensive performance of the alloy was best and the corresponding electrical conductivity and hardness were 42.8 %IACS and 286.1 HV,respectively.(5)The TC-PRISMA was used to simulate the concentration of Si in matrix as well as the size and volume fraction of precipitated phase in Cu-2.78Ni-1.39Co-1.08Si(wt.%)and Cu-20Ni-20Mn-0.3Nb-0.3Cr-0.1Zr(wt.%)alloys during aging,respectively.The electrical conductivity of Cu-2.78Ni-1.39Co-1.08Si(wt.%)alloy and the strength of Cu-20Ni-20Mn-0.3Nb-0.3Cr-0.1Zr(wt.%)alloy were predicted by using the simulated microstructure parameters and the aging strengthening equation,respectively.And the predited results were verified by the experimental oens.This work aims to realize the quantitative simulation and performance prediction of copper alloy solidification and hot working process by establishing Cu alloys mobility database.The correlation analysis of composition,process,structure and performance was carried out,which provided theoretical guidance for the synergistic improvement of strength and electrical conductivity of copper alloys by adjusting composition and process design.