Development of the precipitation and dispersion hardened powder metallurgy Cu-Ni-Si-Cr + Al2O3 alloy

Abstract

A Cu-Ni-Si-Cr + Al2O3 alloy, which combines the precipitation and dispersion hardening of the alloy, were produced by using the powder metallurgy (P/M) technique. To obtain the optimal properties of the alloy, a series of solution and aging treatments were conducted. Following heat treatments, the microstructural, thermal and mechanical properties of P/M produced Cu-Ni-Si-Cr + Al2O3 alloy were investigated.The microstructural investigation indicates that the as hot-forged P/M Cu-Ni-Si-Cr + Al2O3 alloy consists of Cu-Ni-Si-Cr powder (considered as grain A) and Cu-Al2O3 powder (considered as grain B). After heat treatments, it is observed that massive Ni and minor Si elements from grain A diffuse to grain B and react with each other, resulting in the formation of the β-Ni3Si strengthening phases in both grains. Also, Al2O3 dispersoids, which disperse in grain B, provide the high thermal stability in grain size. Therefore, the P/M-produced copper alloy developed in this study has a combination of the better thermal stability in relation to grain size, high strength or hardness and high thermal conductivity, which offers possible applications at elevated temperatures.