The improvement of room temperature plasticity of refractory high entropy alloy based on different first principles calculation models and experiment verification

Abstract

The limited ductility of Refractory High Entropy Alloy (RHEA) at room temperature hinders its widespread application. However, optimizing their properties through traditional “trial and error” methods is a challenging due to the intricate composition of High Entropy Alloys (HEAs). First principles calculation is an efficient and cost-effective method for predicting material properties. Three modeling methods for high entropy alloys are the most commonly used, namely Supercell (SC), Special quasi-random structure (SQS) and Virtual crystal approximation (VCA). To improve the plasticity of NbMoTaTiV at room temperature, the effects of Ti and Ta contents on the mechanical properties were studied. First principles calculations have been employed to predict the phase structure, elastic properties and electronic structure by three common modeling methods and validated against experimental data. The result revealed that MoNbTaTiV and MoNbTa0.5Ti1.5V RHEAs have BCC structure and increasing Ti and decreasing Ta contributed to enhanced toughness of the alloy. Notably, the three methods demonstrated good accuracy in predicting the effects of Ti and Ta content on the performance of NbMoTaTiV. The VCA method was particularly well-suited for predicting elastic properties, offering a balance between computational accuracy and efficiency. SQS and SC considered the complex atomic occupation in HEAs, making them more suitable for studying the electronic structure.