Drastically improved ductility of an Ir-base alloy by mixing Ir–Nb with Ni–Al

The fcc/L12 coherent structure formed in the quaternary Ir–Nb–Ni–Al alloys. The ductility of quaternary Ir–Nb alloy was drastically improved by mixing with Ni–Al binary alloy. The two investigated alloys exhibited higher high-temperature 0.2% flow stress (e.g. above 1000 MPa at 1200 °C) and better ductility (≈20% both at room temperature and 1200 °C). An excellent balance of high-temperature strength and ductility was obtained. The improvement of ductility was attributed to change the fracture mode from intergranular to transgranular.