Microstructural investigation of Cr–Hf–Si alloys

Cr–Hf–Si alloys with Si concentrations up to 40 at.% were fabricated in order to study solidification microstructures in the metal-rich end of the Cr–Hf–Si ternary system. The microstructures were compared with a liquidus projection that was calculated from the extrapolated Cr–Hf–Si thermodynamic description using the CALPHAD approach. Two ternary eutectic reactions were found: L → Cr2Hf (HT) + Hf2Si + β-(Hf) at approximately Hf–33Cr–3Si and L → Cr3Si + (Cr) + Cr2Hf (HT) at approximately Hf–73Cr–9Si. The ternary phase CrHfSi was also seen. The experimental data agreed with the Hf-rich end of the calculated liquidus projection, and it was suggested how the Cr-rich end could be adjusted to account for the experimental results.