Microstructural characterization of as-cast Cr–Si alloys

Abstract

This work presents results of microstructural characterization of as-cast Cr–Si alloys. The alloys were prepared by arc melting pure Cr (min. 99.996%) and Si (min. 99.998%) powder mixtures under argon atmosphere in a water-cooled copper crucible with nonconsumable tungsten electrode and titanium getter. The phases were identified by scanning electron microscopy (SEM), using the back-scattered electron (BSE) image mode and X-ray diffraction (XRD). The results confirm the currently accepted Cr–Si phase diagram in terms of the invariant reactions and solid phases present in this system. Small corrections are proposed for the compositions of the liquid phase in the following reactions: (i) L ⇔ Cr SS+Cr 3Si, from 15 to 16 at.% Si; (ii) L+αCr 5Si 3 ⇔ CrSi, from 51 at.% Si to slightly above 53 at.% Si; (iii) L ⇔ CrSi+CrSi 2, from 56 to slightly above 57 at.% Si; (iv) L ⇔ CrSi 2+Si, from 82 to slightly above 85 at.% Si.