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The liquidus projection and the invariant reactions associated with the liquid phase in the Zr-Si-Al ternary system were experimentally determined. Seventeen primary phase regions were identified from metallographic observation and analysis of the as-cast microstructures. There are at least sixteen invariant reactions and three local maxima associated with congruent melting in the ternary system. The ZrSi primary solidification region covers a wide range of compositions in the Zr-Si-Al ternary system. A variety of the solidification paths were described.

The phase equilibria and oxidation behavior of Ir–Y binary alloys have been investigated. A phase diagram at the Ir-rich end in the Ir–Y binary system has been proposed on the basis of experimental results. Iridium is found to dissolve little Y in the FCC solid solution. The pure-Ir and Ir–Y binary alloys exhibit severe weight loss upon air-exposure at 1373 K with elapsed time. Protective oxide layers are not formed on the surface of the alloys with Y up to, at least, 20 at.%. The kinetics of the oxidation is controlled by the formation and sublimation of Ir oxides at the surface.

The (Nb)/Nb3Si eutectic alloys in the Nb–Si binary and Nb–Ti–Si ternary systems were unidirectionally solidified in an optical floating zone melting furnace. The effect of solidification rates on microstructures of the alloys is investigated. The coupled growth of (Nb) and Nb3Si is observed in the binary alloy solidified at 10 mm/h. The ternary alloys exhibit the development of discontinuous (Nb) particles within the Nb3Si matrix. The unidirectionally solidified alloys show improved fracture toughness and enhanced high temperature compressive strength as compared with the arc-melted counterparts. The role of an aligned eutectic microstructure in toughening is discussed from the existing models based on the crack bridging and the crack deflection.