Phase constituents of Ir–Nb–Pt–Al quaternary alloys

The phase constituents of Ir–Nb–Pt–Al quaternary system were investigated using a combination of several methods. Two L12 phases (L12–Ir3Nb and L12–Pt3Al) were found to be miscible in this system, and a fully fcc/L12 two-phase structure was observed in all the alloys investigated. A partial isothermal phase diagram at 1500 °C was plotted. The lattice misfit between L12 and fcc phase was found to be small, and a fine two-phase structure could form at a certain heat-treatment temperature. The microstructure of Ir–Nb–Pt–Al quaternary alloys showed promising characteristics for the development of high-temperature materials.