Phase equilibria in the Zr-Co-Sn system.

Phase equilibria upon crystallization in the Zr-Co-Sn system were experimentally studied by a combination of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential thermal analysis (DTA). The liquidus projection, melting diagram (liquidus + solidus), vertical sections, Scheil reaction scheme, and isothermal sections at 1000 and 1200 °C covering the whole concentration range were constructed. Four ternary intermetallic phases ZrCo 2 Sn (τ 1), ZrCoSn (τ 2), Zr 6 Co 1.65 Sn 1.35 (τ 3) and Zr 5 Co 6 Sn 18 (τ 4) are confirmed. It is shown that ZrCo 2 Sn (τ 1) and ZrCoSn (τ 2) melt congruently at 1470 and 1340 °C, respectively, while Zr 6 Co 1.65 Sn 1.35 (τ 3) and Zr 5 Co 6 Sn 18 (τ 4) form by peritectic reactions L + Zr 5 Sn 3+x ⇄ τ 3 and L + τ 1 + τ 2 ⇄ τ 3 at 1270 and 1130 °C, respectively. The binary phases Zr 5 Sn 3+x and ZrCo 2 (Laves phase) have extended homogeneity ranges in the ternary system. A total of twenty-four four-phase invariant reactions are established: one peritectic, six eutectic, one eutectoid and sixteen U-type. [Display omitted] • Phase relations in the ternary Zr-Co-Sn systems over the whole concentration range were studied. • Liquidus surface, isothermal and vertical sections and a Scheil diagram were constructed. • Four ternary intermetallic phases ZrCo 2 Sn, ZrCoSn, Zr 6 Co 1.65 Sn 1.35 and Zr 5 Co 6 Sn 18 are formed. • Twenty-four four-phase invariant reactions are established. [ABSTRACT FROM AUTHOR]