Microstructural characterization of as-cast Co–Si alloys

This work presents results of microstructural characterization of as-cast Co–Si alloys. The alloys of different compositions were prepared by arc melting Co (min. 99.97%) and Si (min. 99.99%) under argon atmosphere in a water-cooled copper crucible with a nonconsumable tungsten electrode and titanium getter. All samples were characterized by scanning electron microscopy (SEM) using back-scattered electron (BSE) mode and X-ray diffraction (XRD). A good conformity between the currently accepted Co–Si phase diagram and the experimental results from this work was verified. No indication of the βCo2Si was observed in the as-cast microstructures. As in previous investigations, the Co3Si phase has not been observed in the samples at room temperature; however, microstructural evidence suggests its stability at high temperature.