Influence of severe plastic deformation of Cu powder and space holder content on microstructure, thermal and mechanical properties of copper foams fabricated by lost carbonate sintering method

Abstract

Micro-porous copper foam with open cell structure and acceptable mechanical behavior charts a path for developing the supreme chips and integrated circuit due to its large surface area and good thermal conductivity. In this study, semi-open cell structure copper foams were successfully produced using mechanically pre-activated (milled) Cu powders by different milling durations and 50–70 vol% K2CO3 as a filler material by lost carbonate sintering (LCS) method. The effect of mechanical milling of the used powder and volume fraction of K2CO3 on the microstructure, porosity, strength, energy absorption, and the cooling rate of the produced foam was examined. Microstructural analysis showed that long-duration milled powder creates foams with small pores and homogeneous size distribution, leading to plateau stresses up to ≈170 MPa. Cu foam with increased porosity showed a reduction in yield strength, plateau stress, and energy absorption but a significant increase in its cooling rate. The foam with 70% porosity prepared using 2.5h-milled Cu powders exhibited the highest cooling rate. The results of this study show that the fabrication of Cu foams using flake Cu powder obtained from short-time milling yields improvements in the mechanical and thermal performance of the foam. Mechanical milling of the used powder for a longer time leads to a decrease in cooling rate of the produced foam.