Dendrite structure-induced tunable plastic deformation behavior in (Ti-V-Cr)100-xWx refractory high entropy alloys

Abstract

Inducing multiple deformation mechanisms to improve the plasticity of refractory high entropy alloys (RHEAs) is crucial for their engineering applications. In this work, the dendrite structure-induced deformation behavior in a series of novel (TiVCr)100-xWx (x = 5, 7.5, 12.5, 15 at.%) RHEAs was investigated. The formation of dendrite structures was confirmed by both theoretical (CALPHAD) and experimental methods, and the relationship between dendrite structure and mechanical properties was established. The findings indicated that the volume of interdendrite was conducive to enhance the fracture strain while the finer dendrite benefited the increase of yield strength. With the change of dendrite structure, the plastic deformation mode of the RHEAs also changed accordingly. The slip bands tended to concentrate in the interdendrite, and propagate along the softer interdendrite regions while being hindered by the harder dendrite. The dendrite refinement strengthening, as well as the solid solution strengthening contributed to the strength enhancement. Overall, the present (TiVCr)100-xWx RHEAs demonstrated high specific yield strength and good plasticity when compared with the similar W-containing HEAs. The present findings not only give more insight into the deformation behavior in RHEAs, but also provide a potential strategy to tune the mechanical properties of RHEAs with dendrite structures.