Using differential thermal analysis, X-ray diffraction, microscopy and electron microprobe, phase equilibria in the Ti-rich corner of the Ti–Si–Ge–Al system were studied. Projections of the solidus and liquidus surfaces were constructed. At the solidus temperatures Ti5(Si,Ge,Al)3 (Z) phase coexists with < β-Ti >-based solid solution (β), resulting in a wide two-phase β + Z region. The solidus surface has a temperature maximum at 1540 °C for 70Ti-5Si-5Ge-20Al. The isopleth at 5 at.% Si + 5 at.% Ge is given. The liquidus surface is characterised by the bivariant eutectic surface L ↔ β + Z. Microhardness of the primary phases, corresponding to the boundaries of the homogeneity ranges, and eutectic mixtures was measured.
Partial substitution of silicon for germanium does neither change the character of the phase equilibria nor the temperatures of phase transformations.
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