Microstructure and properties in QCr0.8 alloy produced by selective laser melting with different heat treatment

Abstract

QCr0.8 alloy is promising in many industrial applications because of its extremely high strength and conductivity. In this study, the influences of heat treatments on the microstructure, mechanical properties, electrical properties and corrosion performances of QCr0.8 alloy fabricated by selective laser melting have been investigated. The results show that a threshold solution heat treatment (SHT) temperature exists. Solid solution only happens when the SHT temperature is higher than the threshold. The threshold SHT temperature is higher than that of cast-state. Solution heat treatment leads to a decrease in the dislocation density and dissolution of the precipitates, which induces a reduction of yield strength and conductivity but an enhancement of ductility and corrosion resistance. After directly aging treatment, the Cr phases precipitate from Cu matrix with the size about 5 nm and have K–S relationship with the matrix. Thus, the strength and conductivity are the highest, while the corrosion resistance is the lowest. Different performance match can be obtained by using different heat treatments. These results provide a guideline for to tailor different properties of selective laser melted Cu–Cr alloys using suitable solid solution and aging treatments.