Microstructure and Properties of Rare-Earth B4C–Copper Composites

Abstract

The B4C/Cu composites were prepared by powder metallurgy. Scanning electron microscopy, transmission electron microscopy, hardness tester, conductivity meter, and other analytical tests were used to study the effects of alloying elements and rare-earth modification processes on the microstructure and properties of composites. The results showed that the B4C/Cu composites prepared by powder metallurgy were densely packed, and the Y2O3 modified layer was uniformly coated on the surface of B4C particles. The modified B4C particles had a good interface with Cu and no interfacial reaction occurred. The addition of low melting point alloying element Bi could improve the hardness and electrical conductivity of B4C/Cu composites, but had little effect on the thermal conductivity. Surface modification of B4C with rare-earth salt could effectively increase the bonding ability between B4C particles and Cu, and endowed B4C/Cu composite materials with excellent physical and mechanical properties. For the composite with 2 wt% B4C particles, 2 wt% Bi particles, and 96 wt% copper powder, B4C/Cu composites had good mechanical and physical properties, of which the hardness was 179 HB; the density was 99.6%; the electrical conductivity was 66 %IACS; and the thermal conductivity could reach 262 W/m °C. These properties meet the requirements of electrical contact materials.