Effect of Nb additions on the microstructure, thermal stability and mechanical behavior of high pressure Zr phases under ambient conditions

► We analyze the influence of Nb additions on the shear-induced α → ω → β phase transformations in pure Zr by high pressure torsion (HPT). ► Nb reduces the transition pressures and increases the transformation kinetics. ► High pressure phases are retained under ambient conditions due to the presence of an internal stress. ► Post-HPT annealing allows to fabricate bimodal/biphase nanostructures with enhanced mechanical behavior.