Improving high temperature properties of Cu-Cr-Y alloy by residual Cr particles and nano-Y2O3 dispersions

Advanced Cu-Cr alloys with high strength and thermal conductivity are promising heat dissipation materials but their applications are restricted to low and medium temperatures (<450 °C) due to the coarsening of Cr nanoparticles and grain recrystallization. In this study, a Cu-Cr-Y alloy strengthened by nano-Y2O3 dispersion (ODS Cu-Cr-Y alloy) was prepared by mechanical alloying using atomized Cu-Y alloy, Cr and Cu2O as Y source, microalloying element and oxidant material, respectively. The microstructure and high temperature (600 °C) properties of ODS Cu-Cr-Y alloy were investigated. It was found Y2O3 nanoparticles with ultrafine particle size (8.35 nm) and high number density (2.16 × 1023/m3) were distributed homogeneously in Cu matrix and residual Cr particles (50–100 nm) were formed on grain boundaries. The high temperature tensile strength and softening resistance of ODS Cu-Cr-Y alloy far exceeded that of traditional Cu-Cr alloys, which can be attributed to the thermodynamic stability of nano-Y2O3 dispersions and the inhibition of Cr nanoparticle growth by Y addition and residual Cr particles. The ODS Cu-Cr-Y alloy provides an optimal combination of strength and thermal conductivity at high temperature, showing great promises to be used as heat dissipation material under severe conditions like those in fusion plants and rocket engines.