Phase equilibria in the Ir-rich portion of the Ir-Al-X (X: Ti, Zr and Hf) ternary systems

Isotherms of the Ir-rich portion of the Ir-Al-X (X: Ti, Zr, Hf) systems are presented. In all of the isotherms three-phase equilibrium is found and no ternary compound is observed. Solid solubility of each phase is confirmed by chemical analysis by wavelength dispersive X-ray spectroscopy (WDS). The direction of the solubility lobe of L12-Ir3X with Al addition is explained in terms of the nearest neighbor interactions. Liquidus surfaces are also established by taking into account the microstructure of as-cast alloys, differential thermal analysis (DTA) data, Ir-X binary phase diagrams reported previously and the phase equilibria of the Ir-Al binary system investigated in the present study.