The melting diagram of the Ti–Zr–Sn system below 40 at.% Sn

Abstract

By the methods of DTA, X-ray diffraction, metallography and EPMA, phase equilibria in the Ti–Zr–Sn system at <40 at.% Sn were studied. The partial liquidus and solidus projections, and the melting diagram (solidus + liquidus) were constructed. The liquidus surface is characterized by the presence of primary crystallization regions of (βTi) (β), (Ti 3Sn) (α 2) and (Ti,Zr) 5Sn 3 (5/3) phases. The solidus surface is characterized by the presence of two three-phase fields, β + α 2 + 5/3 and α 2 + (Ti 2Sn)(2/1) + 5/3. The first one results from an invariant four-phase equilibrium L U + α 2 ↔ β + 5/3 taking place at 1510 ± 10 °C. The invariant point U is located at the composition ∼53Ti–30Zr–17Sn. The second three-phase region results from an equilibrium at 1515 °C with participation of L + α 2 + 5/3 + 2/1 phases. The character of the equilibrium is not determined. Two invariant three-phase equilibria were found, L e 1 ↔ α 2 + 5 / 3 at 1600–1650 °C and L e 4 ↔ β + 5 / 3 at 1423 °C.