Interface alloying design to improve the stability and cohesion of W/HfC interface by first-principles study

Tungsten (W) and its composites have been regarded as the most promising candidate plasma-facing materials (PFMs) for fusion reactors due to its exceptional properties. In this work, we systematically investigated the effects of alloying elements (i.e., main groups, 3 d-, 4 d- and 5 d-transition metals) on the stabilities and cohesion properties of the W/HfC interface by first-principles calculations. It is found that the alloying atoms of all main groups and transition metals of group VIB to IIB tend to segregate at the interface and increase the interface stability. In addition, when the alloy atom is doped, the change of interfacial bonding strength is highly correlated with the variation of bond length between interfacial atoms, and a linear model was proposed to account for most of the variations in the relative work of separation, with a R ² value of 0.94. Among these alloying elements, Re was found to enhance the cohesion strength of W/HfC interface by forming a strong Re-C bond based on the electronic structure analyses, and it is universal for Re to enhance the interfacial bonding strength in other W-transition metal carbide composites. This work provides a theoretical guidance for screening alloying elements that can improve mechanical properties of carbides dispersed W alloy in experiments.