Experimental study of the phase relations in the Co–Si–Zn ternary system at 723 and 873 K

The 723 and 873 K isothermal sections of the Co–Si–Zn system have been determined using equilibrated alloys with the aid of a diffusion couple approach. The specimens were investigated by means of scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, electron probe microanalysis and X-ray diffraction. There are nine three-phase regions exist in the isothermal section at 723 K and eight three-phase regions at 873 K. The CoSi phase can coexist with all compounds in Co–Zn binary system except β1 phase. The solubility of Si in Co–Zn binary compounds is limited. The maximum solubility of Zn in CoSi2, CoSi and Co2Si is 2.0, 6.2, and 5.4 at.%, respectively.

► Nine tri-phase regions exist in the Co–Si–Zn system at 723 K.
► Eight tri-phase regions exist in the Co–Si–Zn ternary system at 873 K.
► The CoSi phase can coexist with all compounds in Co–Zn binary system except β1 phase.
► The solubility of Si in Co–Zn binary compounds is limited.
► Zn solubilities in CoSi and Co2Si are higher than that in CoSi2.