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.