Microstructure evolution and property strengthening of CuCr50 prepared by thermite reduction-electromagnetic casting during the heat treatment process

Abstract

A homogeneous CuCr50 alloy ingot prepared in situ by thermite reduction-electromagnetic casting is a type of nonequilibrium solidification structure with a Cu matrix supersaturated with Cr. In this study, the effects of heat treatment on the microstructure of the CuCr50 alloy were studied using scanning electron microscopy (SEM), metallography microscopy and transmission electron microscopy (TEM), and the conductivity, macrohardness and tensile strength of the CuCr50 alloy were measured. The obtained results show that the optimal heat treatment conditions are solution treatment (975 °C for 1 h) and aging treatment (500 °C for 2 h), for which the hardness, conductivity, and tensile strength of the CuCr50 alloy are the best; the macrohardness is 103.33 HB, the conductivity is 18.60 MS/m, and the tensile strength is 199.72 MPa. TEM characterization showed that nanosized Cr particles were precipitated and dispersed in the Cu matrix after the aging treatment; the relationship between the precipitates and the Cu matrix was incoherent, and Cu dissolved into the Cr phase in the form of a solid solution to strengthen the second Cr phase.