Effects of V on the microstructure and mechanical properties of HfNbTaTiVx refractory multi-principle element alloys: A combined experimental and computational study

Refractory multi-principle element alloys (RMPEAs) represent a promising class of high-temperature structural materials due to their excellent high-temperature mechanical properties. An important challenge in the application of RMPEAs is achieving a suitable balance between high strength and ambient ductility. Previous investigations have suggested that vanadium (V) element plays a key role in maintaining the high strength and ductility of RMPEAs. Nevertheless, the fundamental mechanisms by which V influences the strength and ductility of RMPEAs remain unclear. To address this issue, a series of HfNbTaTiVx (x = 0.00–1.00) alloys were designed to investigate the effects of V content on the microstructural and mechanical properties of RMPEAs. The results demonstrate that the prepared HfNbTaTiVx alloys are single-phase body-centered cubic (BCC) solid solutions. V addition helps to improve the tensile yield strength of the alloys while concurrently preserving their ductility. The tensile yield strength increases from 729 MPa (x = 0.00) to 997 MPa (x = 1.00) with the increase of V. Impressively, the HfNbTaTiV0.25 alloy exhibits a tensile fracture plastic strain of 21.9%, which surpasses most existing RMPEAs. The increase in yield strength mainly comes from the intensification of local lattice distortion and solid solution strengthening caused by the introduction of V. Furthermore, the addition of V helps to decrease the elastic anisotropy of the alloys, which is advantageous for their processing quality. Overall, this study not only elucidates the role of V in conferring strength and ductility to RMPEAs but also provides valuable insights for the development and industrial application of RMPEAs.