First principles prediction of yield strength of body centered cubic structured high entropy alloys

Abstract

High entropy alloys (HEAs) with a body centered cubic (bcc) crystal structure have emerged as potential high-performance structural materials due to their high strength at room and elevated temperatures. In this study, a computational approach, based on the revised Peierls-Nabarro model and using the inputs solely calculated from the first principles density functional theory, has been developed to predict the yield strength of bcc HEAs. Examining its accuracy and reliability, the developed computational approach was applied to four different types of bcc HEAs. The yield strength was predicted to be 1034 MPa for MoNbTaW, 1489 MPa for MoNbTaV, 1356 MPa for AlCoCrFeNi, and 1740 MPa for AlCoCrFeNiZr0.3 alloy, respectively. These computational predictions are found to agree well with available experimental data. Moreover, the developed computational approach accurately quantifies the changes in the yield strength from MoNbTaW to MoNbTaV with a change of constituent W to V, and from AlCoCrFeNi to AlCoCrFeNiZr0.3 with addition of 6 at% Zr. Therefore, this first-principles based computational approach provides a way for expedite optimization on the mechanical properties of bcc HEAs across vast composition space.