Investigation on the Microstructures and Thermophysical Properties of Cu-Fe64Ni32Co4 Alloys

Abstract:

Based on the CALPHAD approach and vacuum arc melting technology, the Cu_x(Fe_0.64Ni_0.32Co_0.04)_100-x(x=30, 45, 60, wt. %) series alloys were designed and prepared. The effects of annealing process on microstructures, thermal conductivity (TC) and thermal expansion coefficients (CTE) were investigated in 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 °C and 800 °C. After annealing at 600 °C for 50 h, the CTE of the alloys ranged from 6.88 to 12.36×10_-6 K_-1. And TC varied from 22.91 to 56.13 W.m_-1.K_-1. Particularly, the TC are significantly higher than that of Invar alloy, and the CTE of Cu₃₀(Fe_0.64Ni_0.32Co_0.04)₇₀ and Cu₄₅(Fe_0.64Ni_0.32Co_0.04)₅₅ alloys can well match with that of semiconductor in electronic packaging.

Key words:CALPHAD approach; Cu-Fe₆₄Ni₃₂Co₄; microstructures; thermal conductivity; thermal expansion coefficients