Fabrication and characterization of Y2O3 dispersion strengthened copper alloys

Abstract

Three copper base materials were fabricated following different routes: cast Cu–1wt.%Y (C-Cu1Y) produced by vacuum induction melting, and Cu–1wt.%Y (PM-Cu1Y) and Cu–1wt.%Y2O3 (PM-Cu1Y2O3) both processed by a powder metallurgy route and sintering by hot isostatic pressing. PM-Cu1Y alloy was prepared by cryomilling and PM-Cu1Y2O3 by conventional milling at room temperature. The materials were characterized by X-ray diffraction, optical and electron microscopy and microhardness measurements. C-Cu1Y presents a characteristic eutectic microstructure while PM-Cu1Y2O3 exhibits a composite like microstructure. Electron microscopy analyses of as-HIP PM-Cu1Y revealed irregular decoration of yttrium-rich oxides at the grain boundaries and an inhomogeneous dispersion of polygonal shaped yttrium-rich oxides dispersed in the Cu matrix. Tensile tests performed on PM-Cu–1Y on the temperature range of 293–773K have showed a decrease of the yield strength at temperatures higher than 473K, and monotonically decrease of the ultimate tensile strength and maximum plastic strain on increasing temperature.