A Thermodynamic Modelling of the Stability of Sigma Phase in the Cr-Fe-Ni-V High-Entropy Alloy System
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The addition of vanadium (V) to the representative Co-Cr-Fe-Mn-Ni high-entropy alloy (HEA) system is attracting attention expecting a large solid solution hardening effect. For the design of V-added HEAs, prediction of the sigma (σ) phase formation has been mainly issued because it affects a significant influence on the mechanical properties. Although the CALculation of PHAse Diagram (CALPHAD) approach can be a good tool for prediction of phase structures, robust thermodynamic database is still required for an accurate prediction of V-added HEA systems. The present work aims at providing a thermodynamic description for the Cr-Fe-Ni-V HEA system, focusing on the thermodynamic stability of the σ phase. A parameterization technique which minimizes the number of fitting parameter and simplifies the extension into higher-order systems is proposed and applied to the σ phase with multiple sublattice during modelling the Cr-Ni-V and Fe-Ni-V systems. The reliability of the developed thermodynamic description for the Cr-Fe-Ni-V quaternary system is experimentally confirmed by designing, fabricating and analysing the phase structures of a series of Cr-Fe-Ni-V HEAs.
KeywordsCALPHAD Cr-Fe-Ni-V high-entropy alloy sigma phase thermodynamic modelling
This research was supported by the Future Material Discovery Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT of Korea (2016M3D1A1023383).
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