New developed quaternary refractory superalloys

The novel idea for designing quaternary superalloys by two kinds of binary alloys with coherent structure was applied to Ir–Nb–Ni–Al superalloys. Eight alloys were prepared by combining two sorts of binary alloys, Ir–Nb and Ni–Al, in different proportions. The effects of the mole fraction of Ir-based alloy or the L12 alloy on the microstructure and the 0.2% flow stress of quaternary alloys were investigated. Two sorts of coherent structure, fcc/L12–Ir3Nb and fcc/L12–Ni3Al, were observed in the quaternary superalloys. The new developed quaternary Ir-based superalloys are of the advantages of Ir-based alloys and Ni-based superalloys. The 0.2% flow stress of Ir–Nb–Ni–Al at 1200°C could reach up to 350 MPa and the compressive strains were improved greatly compared with Ir-based alloys.