Experimental investigation of phase equilibria in the Co-Si-Zr ternary system

The phase equilibria in the Co-Si-Zr ternary system were investigated by means of back-scattered electron (BSE), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Two isothermal sections of the Co-Si-Zr ternary system at 1273 and 1373 K were experimentally established, and the compositions of the two ternary compounds (Zr5Co8Si9 and Zr4Co4Si7) were confirmed. The isothermal sections of the system at 1273 and 1373 K respectively consist of 29 and 30 three-phase regions, and also six ternary compounds was found in both two isothermal sections. The solubility of Zr in the intermediate and solution phases (i.e. αCo2Si, αCoSi, CoSi2, αCo and εCo) at the Co-Si side is extremely small, whereas the situation of Si in the Co-rich corner (especially for Co23Zr6 and Co2Zr phases) is reverse.