Simultaneous enhancement of strength and ductility of body-centered cubic TiZrNb multi-principal element alloys via boron-doping

Abstract Body-centered cubic (BCC) multi-principal element alloys (MPEAs) have intrinsic high strength but poor ductility, which greatly limits their potential applications. Here we present the boron-doping strategy to enhance the strength and ductility of TiZrNb MPEAs simultaneously. The yield strength and ductility of the TiZrNb MPEA with boron addition of 500 ppm are increased by 19.0 % and 48.7 % compared to the boron-free TiZrNb MPEA, respectively. Boron-doping induced high efficiency in grain refinement from ∼96.0 μm to ∼16.2 μm is the main factor for strengthening. Dislocation dominated deformation mechanism involving cross slip and dislocation pining in the TiZrNb containing 500 ppm boron serves to enhance the strain-hardening capacity, resultant the enhancement of ductility from 7.8 % to 11.6 %. While the planar slip of dislocations is the dominated deformation mechanism for the boron-free TiZrNb.