| Abstract Scope |
Refractory compositionally complex alloys (R-CCAs) are a promising next generation class of materials for extreme environments, particularly at elevated temperatures. However, R-CCAs research to date has identified a critical dichotomy between high temperature strength retention and room temperature ductility. Derivatives of the so-called Senkov alloys, equiatomic HfNbTaTiZr, exhibit excellent room temperature ductility but poor strength retention at temperatures above 1300 K. Meanwhile, alloys containing considerable fractions of Group VI elements, namely Mo and/or W, possess outstanding strength and strength retention at temperatures well above 1300 K, but exhibit brittle tensile behavior at room temperature, limiting their practical applications. This work will discuss the underlying mechanisms that give rise to both tensile ductile/brittle behavior and elevated temperature strength. We demonstrate that Mo-/W-containing alloys can be intrinsically ductile, and high temperature strength retention and tensile ductility can be achieved through careful consideration of both intrinsic and extrinsic contributions to macroscopic mechanical behavior. |