Pinning effect of Y2O3 network on copper grain growth during high temperature annealing

Abstract

Ultrafine-grained copper matrix composites, with a network of yttria (Y2O3) nanoparticles, were fabricated via a novel route combining high-energy milling, two-step reduction, and spark plasma sintering. The effect of yttria nanoparticle content in the network on the thermal stability of the ultrafine copper grains was investigated by annealing at temperatures ranging from 400 to 900 °C for 1 h. The thin and high-density network with 4 vol.% Y2O3 nanoparticles in the copper matrix was found to exhibit better thermal stability and its softening temperature was at 900 °C. In contrast, at 8 vol.% of Y2O3 nanoparticles, the thickness of the Y2O3 network in the matrix increased and its density decreased, reducing the pinning effect on the copper grain growth and increasing the coarseness of the Y2O3 network in the matrix during the isochronal annealing at 800 °C.