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

Abstract

Abstract Phase equilibria in the Ti–Dy–Sn system below 40 at.% Sn were studied using differential thermal analysis, X-ray diffraction, metallography and electron microprobe. The partial liquidus and solidus projections and the melting diagram (liquidus + solidus) were constructed. A new ternary compound τ with composition Ti4.2–4.3Dy0.8–0.7Sn≲3, found by us previously, melts congruently above 1 543 °C and coexists with all the phases based on the binary compounds of the boundary binaries in the concentration interval studied. The liquidus surface is characterized by primary crystallization regions of (βTi), (βDy), (αDy), (Ti3Sn), (Ti2Sn), (Ti5Sn3), (Dy5Sn3) and τ. Five three-phase fields in the solidus surface result from three eutectic and two transition type invariant four-phase equilibria: LE1 ⇄ (βTi) + (Ti3Sn) + (Dy5Sn3), LE2 ⇄ (Ti3Sn) + τ + (Dy5Sn3), LE3 ⇄ (βTi) + (αDy) + (Dy5Sn3), LU1 + (Ti2Sn) ⇄ (Ti3Sn) + τ and LU2 + (Ti2Sn) ⇄ (Ti5Sn3) + τ at 1 524, 1 500, 1 150, 1 543 and 1 498 °C, respectively. In the two-phase areas (βTi) + (Dy5Sn3), (Ti3Sn) + (Dy5Sn3), (Ti2Sn) + τ and τ + (Dy5Sn3) the solidus surface has the temperature maxima at 1 620, 1 540, > 1 543 and > 1 500 °C, respectively.