|About this Abstract
||MS&T23: Materials Science & Technology
||Grain Boundaries, Interfaces, and Surfaces: Fundamental Structure-Property-Performance Relationships
||Chemical Ordering Delays Grain Boundary Complexion Transitions in NbMoTaW
||Ian Geiger, Timothy J. Rupert
|On-Site Speaker (Planned)
Complex chemical domains in multi-principal element alloys create new challenges in predicting interfacial structure. In this study, we use atomistic modeling to explore the effect of segregation and local chemical ordering on grain boundary complexion transitions in a NbMoTaW refractory alloy. Using hybrid Monte Carlo/molecular dynamics simulations, we show that the structural disordering of a high-angle boundary is highly sensitive to the local chemical environment, resulting in a structural transition range more than twice that of a comparable pure metal. In addition to thermodynamic considerations, analysis of interface kinetics reveals that the strong influence of local chemical order on boundary diffusivity also contributes significantly to the elongated transition. For example, Nb and Ta interfacial diffusivities decrease seven-fold in a chemically ordered environment as compared to a random solid solution. Overall, our work highlights the critical role of complex chemical domains on interface stability and transitions in grain boundary structure.