High tensile ductility and strength in a gradient structured Zr

We report that a gradient structured Zr processed by asymmetric rolling and partial annealing possesses an exceptional synergy of high strength (sigma(y) similar to 550 MPa) and high tensile ductility (epsilon(u) similar to 10.1%) much better than that (sigma(y) similar to 250 MPa and epsilon(u) similar to 14.2%) of its coarse-grained (CG) counterpart. This gradient structure is characterized by a gradient dislocation density distribution from the surface to the core and composed of microscale and ultra-fined elongated grains connected by low angle grain boundaries (LAGBs). These findings can provide valuable insight for designing gradient structures with excellent mechanical properties. (C) 2018 Elsevier B.V. All rights reserved.