Microstructures and Thermophysical Properties of Cu-Fe64Ni32Co4 Alloys

Based on the calculation of phase diagrams (CALPHAD) approach and vacuum arc melting technology, the Cu-x(Fe0.64Ni0.32Co0.04)(100-x)(x=30, 45, 60, wt%) series alloys were designed and prepared. The effects of annealing process on microstructures, thermal conductivity (TC) and coefficient of thermal expansion (CTE) were investigated for these prepared alloys. The result shows that the Cu-Fe64Ni32Co4 isotropic polycrystalline alloys present two separate fcc phases (fcc Cu-rich phase and fcc (Fe, Ni, Co)-rich phase) microstructures after annealing at 600 and 800 degrees C. After annealing at 600 degrees C for 50 h, the CTE of the alloys ranges from 6.88x10(-6) to 12.36x10(-6) K-1 and TC varies from 22.91 to 56.13 W.(m.K)(-1). The TC are significantly higher than that of Invar alloy, and the CTE of Cu-30(Fe0.64Ni0.32Co0.04)(70) and Cu-45(Fe0.64Ni0.32Co0.04)(55) alloys can well match with that of semiconductor in electronic packaging.