Microstructural Evolution and Mechanical Behaviour of Metastable Cu–Zr–Co Alloys

Three different Cu–Zr–Co alloys, namely Cu 40 Zr 37.5 Co 22.5 , Cu 42.5 Zr 45 Co 12.5 and Cu 49 Zr 49 Co 2 , were obtained by rapid cooling. The microstructure and phase formation of as-cast rods with diameters of 2 mm are compared with those of the respective ingots. An increasing Co content stabilises the B2 CuZr phase and leads to the precipitation of a ternary Cu–Zr–Co phase. The variation of the cooling rate affects the size of the B2 dendrites as well as the volume fraction and the morphology of the interdendritic phases. The mechanical properties were determined in compression and all alloys show a certain plastic deformability despite the presence of several binary and ternary intermetallic phases. The deformation mechanisms are discussed on the basis of the microstructures and the constituent phases.