Bulk nanocrystalline ω-Zr by high-pressure torsion

Pure nanocrystalline Zr with a grain size of 30 nm and a microhardness of 400 HV has been fabricated by high-pressure torsion (HPT) at room temperature using a pressure of 6 GPa and five revolutions in 5 min. Complete transformation and significant refinement from the initial coarse-grained α-phase to the high-pressure ω-phase occurs during processing. The omega nanocrystalline phase is stable at room temperature and atmospheric pressure. The shear strain applied enhances the transformation kinetics.