Atomic insights of grain boundary behaviors in TaWNbMo refractory high entropy alloys

Abstract

Refractory high entropy alloys (RHEAs), such as TaWNbMo, demonstrate promising potential for high-temperature applications owing to their excellent mechanical properties. Given the pivotal role of grain boundaries (GBs) in determining the mechanical behavior of RHEAs, it is imperative to investigate their characteristics. In this work, the mechanical response of TaWNbMo RHEA and its components (Ta, W, Nb, and Mo) bicrystal samples with Σ3{112‾}<110> and Σ3{111‾}<110> GB under shear were performed using molecular dynamics simulations to investigate the motion characteristics of GBs and their influence on mechanical properties, as well as the variations brought by high entropy GBs. Both types of GBs were observed to migrate coupled with shear deformation, and the migration mechanism was analyzed based on the theory of interface defects. Additionally, twin nucleation and growth were observed in the samples with Σ3{111‾}<110> GB influenced by the high GB energy, and its mechanism was analyzed. Furthermore, a comparison was made between TaWNbMo and its component element metals, and the influence of high entropy GBs was analyzed. The multicomponent complexity invoked the local interfacial disconnection nucleation in HEA for both Σ3{112‾}<110> and Σ3{111‾}<110> GBs, the inhomogeneity of HEA also influenced the twin growth process from Σ3{112‾}<110> GB to proceed and thicken in a localized and non-uniform manner. These results contribute to a deeper understanding of the GB characteristics of TaWNbMo RHEA.