Enhancement of yield strength in zirconium metal through high-pressure induced structural phase transition

We report here a high-pressure phase-transition induced strengthening in ultrapure zirconium metal. The determined yield strength shows more than sixfold abrupt increase at the transition pressure of P-c=6 GPa, from sigma(alpha)(y)approximate to 180 MPa in the low-pressure phase of alpha-Zr to sigma(omega)(y)approximate to 1180 MPa in the high-pressure phase of omega-Zr. The observed enhancement provides an alternate route for material strengthening and is the most significant among the known strengthening techniques for metals. Our findings support the theoretical simulations of the substantial covalent bonding and rougher corrugation of slip planes for dislocations in the omega-phase of zirconium. (c) 2007 American Institute of Physics.