The design and application of high‐tungsten (W) superalloys represent an effective strategy for enhancing the high‐temperature performance of superalloys. However, the associated deterioration of mechanical properties caused by high refractory element content remains an urgent issue to be resolved. A model high‐W superalloy with Al contents of 3, 4, 5, and 6 wt% was designed to study the optimization mechanism of Al content. The effects of Al content on the microstructure and stress rupture properties were investigated. The results of thermodynamic calculations and microstructural observation demonstrated that increasing the Al content promoted the precipitation of both the γ′ and α‐W phases. The peak stress rupture life was achieved at an Al content of approximately 5 wt%. This optimum is attributed to the competing strengthening mechanisms: increased Al content enhanced precipitation strengthening but concurrently reduced the solid solution strengthening of W as it partitioned into α‐W precipitates. Thus, the optimized performance at 5 wt% Al resulted from a balance between these mechanisms. The regulation of Al content enabled control over the microstructural morphology, which in turn enhanced the stress rupture life at elevated temperatures. This work provides novel insights and theoretical support for the development and application of high‐W superalloys.
Wang et al. (Tue,) studied this question.