Strength Behavior of Niobium-Based Refractory Systems

A comprehensive assessment of the quasi-static strength behavior of niobium (Nb)-based refractory systems, including the conventional Nb alloys and refractory high-entropy alloys (RHEAs), in a broad temperature range has been performed in this review. The strength and ductility data of the Nb-based refractory systems in varying temperature ranges manufactured by various methods have been compiled and discussed to correlate the manufacturing, material characteristics, deformation, and strength behavior. The microstructure characteristics and the interstitial contaminations have been identified as the dominating factors in controlling strength behavior in the low-temperature range of the Nb alloys. In the intermediate temperature range, the dynamic strain recovery plays a significant role in dictating the strength behavior, while, in the high-temperature domain, the diffusion-assisted deformation process leads to significant strength reduction. Nb-based RHEAs have been found to have great potential for applications in extreme temperatures (> 1200°C). A wide range of strength and ductility is possible in Nb-based RHEAs. Solid-solution strengthening largely controls the variation in strength, ductility, and thermal stability of RHEAs.