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 degrees C covering the whole concentration range were constructed. Four ternary intermetallic phases ZrCo2Sn (T1), ZrCoSn (T2), Zr6Co1.65Sn1.35 (T3) and Zr5Co6Sn18 (T4) are confirmed. It is shown that ZrCo2Sn (T1) and ZrCoSn (T2) melt congruently at 1470 and 1340 degrees C, respectively, while Zr6Co1.65Sn1.35 (T3) and Zr5Co6Sn18 (T4) form by peritectic reactions L + Zr5Sn3+x F T3 and L + T1 + T2 F T3 at 1270 and 1130 degrees C, respectively. The binary phases Zr5Sn3+x and ZrCo2 (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.

Automated summary

The phase equilibria upon crystallization in the Zr-Co-Sn system were studied using SEM, EPMA, XRD, and DTA. Ternary intermetallic phases T1, T2, T3, and T4 were confirmed, with T1 and T2 melting congruently and T3 and T4 forming by peritectic reactions. The system also exhibits extended homogeneity ranges for the binary phases Zr5Sn3+x and ZrCo2.