Investigation of microstructure and thermophysical properties of hot-pressed CuFeCoCr composite

Abstract:

In this paper, series micro-scale powders with composite microstructure in CuFeCoCr system were successfully designed and fabricated by using CALPHAD (Calculated of Phase Diagrams) approach and gas atomization method, respectively. The bulk CuFeCoCr composites were produced by hot pressing technique at 950℃ under a pressure of 45MPa. The effect of Cu content on the microstructure, coefficients of thermal expansion (CTE), thermal conductivity (TC) and micro-hardness (H_V) were systematically studied. The results show that the CuFeCoCr composites present two separate fcc phases (Cu-rich and FeCrCo-rich phase) microstructure. After annealing at 500 °C for 8 h, the CTE of the composites ranged from 5.75 to 11.45×10^_-6 K^_-1 and TC varied from 42.2 to 107.4 W.m^_-1.K^_-1. Particularly, the Cu₅₅(Fe_0.37Cr_0.09Co_0.54)₄₅ composite exhibits excellent comprehensive properties, i.e. CTE of 6.88×10^_-6 K^_-1 and TC of 91.09 W.m^_-1.K^_-1,which matches with the semiconductor in electronic packaging. In addition, all the prepared composites exhibit a higher H_V than that of Cu/Invar composite.

Key words:CALPHAD approach; Composites; Liquid phase separation; Thermal expansion coefficients; Thermal conductivity