Contribution to the Ti–Co–Sn system

• Published in: Calphad Vol. 84; p. 102662
• Main Authors: Fartushna, I., Bulanova, M., Samelyuk, A., Bega, M., Kuzmenko, Y., Tedenac, J.-C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2024
• Subjects: Experimental; Isothermal section; Ti-Co-Sn system; Isothermal section; Experimental; Ti-Co-Sn system
• ISSN: 0364-5916; 1873-2984
• DOI: 10.1016/j.calphad.2024.102662

The ternary phase diagram Ti–Co–Sn was studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Isothermal sections at 1000 and 1200 °C have been determined experimentally for the first time in the entire range of compositions. Thirteen and ten three-phase regions were found at 1000 °C and 1200 °C, respectively. Vertical sections at 10, 20 and 30 at.% Sn were plotted. The most striking feature of the ternary Ti–Co–Sn phase diagram is formation of a ternary compound TiCo2Sn (Heusler phase, τ), which was found at both investigated temperatures. The TiCoSn compound (half-Heusler phase) was not found. Among binary compounds, Ti5Sn3 and TiCo have the widest homogeneity regions. The Ti5Sn3 phase dissolves 10.0 and 9.8 at.% Co at 1200 and 1000 °C, respectively, forming an interstitial solid solution. The solubility of Sn in TiCo is more than 10 at.% at both 1200 and 1000 °C. The remaining binary intermetallic phases hardly dissolved the third component. The liquid phase at 1000 °C mainly exists in the Sn-rich corner, while at 1200 °C it stretches along Co–Sn side spreading from the Sn corner and is also present on the Ti-rich side. In addition, two four-phase invariant transition type reactions TiCo2 (h) + (αCo) ⇄ τ + TiCo3 and TiCo + TiCo2 (h) ⇄ τ + TiCo2 (c) were deduced. [Display omitted] •Phase relations in the ternary Ti–Co–Sn system over the whole concentration range were studied.•Isothermal and vertical sections were constructed.•A ternary compound TiCo2Sn (Heusler phase) was found at 1000 °C and 1200 °C.•The binary phases TiCo and Ti5Sn3 have an extended homogeneity.•Thirteen and ten three-phase regions were found at 1000 °C and 1200 °C, respectively.