Constitution of the ternary system Co–Si–Ti

The constitution of the ternary system Co–Si–Ti was investigated using electron microscopy, energy dispersive spectroscopy, x-ray diffraction, and differential thermal analysis. Eleven ternary phases were identified and their homogeneity ranges characterized. The equilibria between these phases at 1000 °C are presented in an isothermal section. A reaction scheme linking this isothermal section with the liquidus surface is derived. It contains three ternary eutectics at 1195 °C, 1148 °C and 988 °C in the Si-rich, Co-rich and Ti-rich corners, respectively. The liquidus surface projection proposed shows large regions of primary crystallization for the congruently melting ternary phases τ1-CoSiTi and τ2-Co4Si7Ti4, the incongruently melting Laves phase (bundle) τ6, as well as the binary phases CoSi, CoTi, and Ti5Si3.

► The occurrence of 11 ternary Co–Si–Ti phases is established. ► The equilibria among these phases at 1000 °C are given in an isothermal section. ► A reaction scheme linking them with the liquidus surface is proposed. ► A projection of this liquidus surface is given for the first time.