Microstructure and properties of spray cast CuZr alloys

CuZr alloys were produced by spray casting in the Osprey mode with zirconium levels in the range 0.1–0.8 wt.%. Microstructures were characterized and mechanical properties and electrical conductivity monitored in the spray cast condition, and following thermo-mechanical processing. In the spray cast condition, the alloys exhibit a fine equiaxed grain structure with no macro segregation. Two phases are present at the grain boundaries, one of which was identified as Cu 5Zr. This phase is stable during solution treatment and does not contribute to precipitation strengthening on aging. Strengthening during aging is attributed to the formation of zirconium-rich clusters in the copper. The grain boundary network of Cu 5Zr enhances resistance to grain growth during recrystallization. Attractive combinations of tensile strength and electrical conductivity were achieved by thermo-mechanical processing of the spray cast Cu0.4 wt.% Zr alloy, for example 525 MPa/87% international annealed copper standard (IACS). This combination is superior to strength-electrical conductivity combinations in ingot metallurgy or powder-processed CuZr.