Superior mechanical properties of pure Zr with heterogeneous structure

Grain refinement always provides a high strength of metals and alloys but this is accompanied by a remarkable deterioration of ductility. Here we report a pure Zr with a heterogeneous structure, characterized by recrystallized coarse grains embedded in the ultrafine-grained matrix, which is produced by rolling at room temperature and subsequent partial recrystallization. The results show that the heterostructured Zr exhibits a superior combination of high strength and improved ductility and higher strain hardening than its coarse-grained counterparts. In terms of the high strength of heterostructured Zr, it is ascribed to the abundant ultrafine grains and significant hetero-deformation induced strengthening. Whereas good ductility is derived from the dislocation hardening of recrystallized coarse grains, the hetero-deformation induced hardening, and the sharp (0002) basal texture. The present study can contribute to understanding the essence of a desirable combination of strength and ductility of heterostructured materials.