Liquid-solid phase equilibria in metal-rich Hf-Ti-Si alloys

A range of metal-rich Hf-Ti-Si alloys with Si concentrations up to 35.0 at.% was directionally solidified. Liquid - solid phase equilibria in these alloys have been investigated using scanning electron microscopy, X-ray diffraction, and electron beam microprobe analysis. Four phases were identified: (Hf, Ti)₅Si₃, Hf(Ti)2Si, b(Hf, Ti, Si), and a(Hf, Ti, Si). Microstructural and microchemical evidence provided a clear definition of the Hf-Ti-Si liquidus surface at the metal-rich end and indicated the existence of the invariant reaction:.