Phase equilibria in Ni–Ti–Ta ternary system

Abstract

Phase diagrams of two isothermal sections of the Ni–Ti–Ta ternary system at 1000 and 1200 °C in a full composition range were determined by X-ray diffraction and electron probe microanalysis. The experimental results indicated a ternary compound τ phase with low solid solubility and composition ranges of (16.3–22.4) at.% Ta, (15.9–24.1) at.% Ti and (58.5–60.0) at.% Ni at 1000 °C. The two terminal solid solutions (bcc-(Ta) and β-Ti) formed a continuous solid solution at 1000 and 1200 °C. A certain amount of Ti can dissolve into Ni–Ta intermetallic compounds near the Ni–Ta side, with the highest value of 21.9 at.% observed in the Ni2Ta compound at 1000 °C.