Ti-Zr-V-Nb-Al BCC high-entropy alloy with outstanding uniform ductility achieved by grain refinement
Hanlin Zeng, Mengyunqing Han, Bolun Li, Liang Wang, Ke Jin, Benpeng Wang, Shihai Sun, Lu Wang, Yunfei Xue
Abstract
The lack of sufficient uniform deformation ability of body-centered cubic (BCC) high-entropy alloys (HEAs) is the obstacle to their applications as structural materials. Here we present a grain refinement strategy to achieve excellent uniform ductility of a BCC non-equal atomic ratio Ti-Zr-V-Nb-Al (TZ) alloy. The uniform elongation and yield strength of the fine-grained TZ alloy with a grain size of 15 µm are as high as ~12% and 840 MPa, respectively. The outstanding uniform deformability of the fine-grained TZ alloys is due to the frequent cross-slip events and abundant dislocation tangles. Grain refinement can increase the probability of dislocation entanglement, thereby promoting a rise in the work-hardening rate. The good plasticity and high work-hardening rate can improve the uniform deformation ability. Our results will give new insights into enhancing uniform ductility while maintaining high strength in the BCC HEAs.