Hf-Si binary phase diagram determination and thermodynamic modeling

A new version of the Hf-Si binary phase diagram has been constructed and it includes recent confirmation of the existence of the Hf5Si3 phase and obse rvation of the following eutectoid reaction: Hf5Si3 <-> Hf2Si + Hf3Si2 at 1 925 +/- 25 degrees C, The peritectic reaction, L + Hf3Si2 <-> Hf5Si3 at sim ilar to 2360 +/- 30 degrees C, was proposed with consideration of Brukl's i ncipient melting results. Thermodynamic modeling of the binary Hf-Si system was performed via Thermo-Gale with existing phase diagram data, the experi mental results described in this paper, and the reported enthalpies of form ation for Hf silicides, A complete thermodynamic description of the Gibbs e nergies of all stable phases in the binary system was developed and was con sistent with the majority of the phase diagram and thermochemistry data.