Wetting and interfacial behavior of high entropy alloy filler on rare earth silicate system: Phase analysis and first-principles calculations

The vacuum reactive wetting and brazing of Er₂Si₂O₇/MoSi₂ coatings were investigated using a (CoFeNiCrMn)₈₈Nb₁₂ high-entropy alloy (HEA) brazing filler. The microstructural evolution and wettability of the HEA filler were analyzed, with particular attention to the surface energy, interfacial stability, and electronic properties of the HEA filler/rare earth silicate coating system, as determined by density functional theory (DFT). As Nb diffused into the interface and the ErNbO₄ phase formed, the wetting angle gradually decreased to 23.12° The effective wetting and spreading of the HEA brazing filler on the rare earth silicate coating surface are strongly correlated with the formation of the ErNbO₄ phase at the interface. Furthermore, DFT calculations reveal that the interfacial bonding energy between the BCC' and FCC' phases and the ErNbO₄ phase, after the wetting reaction, is significantly higher than the bonding energy between the initial filler and Er₂Si₂O₇. This finding suggests that the formation of the ErNbO₄ phase improves the wetting and spreading behavior of the filler.