Combined effects of metallic dopants and nonmetallic impurities on interface cohesion in tungsten alloys by first-principles

The effect of element segregation on interface cohesion demonstrates significant potential in tailoring the mechanical performances of materials. In this study, we have investigated the impact of co-segregation of transition metal (Re, Zr and Ti) and non-metallic impurity elements (O and C) on the cohesion properties of two typical interfaces, W/HfC phase boundary (PB) and Σ5(310) grain boundary (GB) in W alloys, using first-principles calculations. Our findings reveal that O atom exhibits comparable segregation tendency at both the PB and GB interfaces, but the PB has a stronger resistance to O-embrittlement than the GB. C atom preferentially segregates at the GB and enhances the interface cohesion. In addition, Re atoms tend to segregate at both the interfaces and enhance the interface cohesion. Co-segregation of Zr/Ti and O atoms at the interface leads to a reduction in impurity O concentration within the W matrix, and further decreases the interface cohesion. In contrast, C atom mitigates the GB embrittlement induced by Zr/Ti atom owing to the formation of W-C bonds. This work deepens the understanding of how the co-segregation of alloying and non-metallic impurity elements affects the interface properties, offering theoretical guidance for optimizing the mechanical performance of W-based materials.