Thermodynamic Descriptions of the Co–Zr and Co–Fe–Zr Systems

Abstract

The Co–Fe–Zr system and its Co–Zr subsystem were optimized using the CALculation of PHAse Diagram (CALPHAD) approach. The substitutional solution model was used for describing the phases liquid, fcc_A1, bcc_A2 and hcp_A3. Two Laves phases were modeled as (Co,Fe,Zr)2(Co,Fe,Zr)1, and the phases CoFe and CoZr with the bcc_B2 crystal structure were described as the ordered one of bcc_A2 in the formula (Co,Fe,Va,Zr)0.5(Co,Fe,Va,Zr)0.5Va3. With limited solubility ranges, all other phases were treated as the line compounds (Co,Fe)mZrn. An excellent agreement between the reported and calculated results was reached. The reliable thermodynamic parameters of the Co–Fe–Zr system were acquired, which can be well applied to various thermodynamic calculations and materials design.