Predicting phase formation in complex concentrated alloys from first-principles

Abstract

Using first-principles theory, a new phase-formation prediction model is developed. Results show that the newly developed model can well predict the phase stability between the face-centered cubic (FCC) and body-centered cubic (BCC) in complex concentrated alloys at finite temperatures. Also, the enthalpy of mixing is demonstrated to account for the enthalpy contribution to the free energy of mixing at lower temperatures. Only at higher temperatures does the configurational entropy dominate the free energy of mixing. Moreover, the high magnetic moment on the Fe-sites of BCC structure accounts for the FCC-to-BCC abnormal phase transition in AlCrCuFeNix alloys at high temperatures. Combined with experimental data, the typical AlxCrMnFeCoNi and AlxCrCuFeNi2 systems are adopted to verify the bidirectional predictability and validity of the model. Bain path calculations are also performed to support the predicted phase-formation rules at the ground state.