Experimental investigation of phase equilibria in the Ni–Co–Si ternary system

The phase equilibria of the Ni–Co–Si ternary system have been investigated by electron probe microanalyzer (EPMA) and X-ray diffraction (XRD) on the equilibrated alloys. Three isothermal sections of the Ni–Co–Si ternary system at 1000 °C, 1100 °C and 1200 °C were determined, and no ternary compound was found in this system. The obtained experimental results in the present work show that (1) there is a large α (Ni, Co) continuous solid solution; (2) the extensions of all the binary intermediate phases of the Ni–Si and Co–Si system into the ternary occur along the respective stoichiometric lines of fixed Si contents. The newly determined phase equilibria in this system will provide important support for the development of transition metal silicides and nickel based fillers.

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► Three isothermal sections of the Ni–Co–Si system were experimentally determined.
► The solubility of Ni in the CoSi phase decreases with the temperature increases.
► The solubility of Co in the γ (Ni31Si12) phase decreases from 1100 to 1200 °C.