High temperature thermo-mechanical responses mediated by interfacial microstructure regulation in tungsten heavy alloy/superalloy brazed joints

The plasma-facing components of future fusion reactor applications, where tungsten heavy alloy (WHA) and superalloy dual-metallic structures are promising structural and functional materials, will be fabricated by vacuum brazing techniques. Herein, the mechanistic correlation between multi-interfacial structures from meso-scale to atomic-scale and high temperature thermo-mechanical responses was revealed. Fatigue defect propagation mechanisms induced by thermal cycling load were analyzed, and the orientation relationship of β-Ti/Fe2Ti coherent interface combined with high residual tensile stress in brittle Ni3Ti illustrated the underlying cause of fatigue cracks and intragranular voids. This work provides insight into the critical engineering challenges of WHA dissimilar joining systems and guides future anti-thermal fatigue designs.