Abstract:To investigate potential strengthening approaches, multi-layered zirconium–titanium (Zr-Ti) composites were fabricated by hot-rolling bonding and annealing. The microstructures of these composites were characterized using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and electron backscatter diffractometry (EBSD). Their mechanical properties were evaluated by uniaxial tension and compression measurements. It was found that the fabricated Zr–Ti composites are composed of alternating Zr/diffusion/Ti layers, and chemical compositions of Zr and Ti showed a gradient distribution in the diffusion layer. Compared with as-rolled samples, annealing can strengthen the layered gradient Zr–Ti composite, and this is mainly caused by solid-solution strengthening and microstructure refinement-induced strengthening. Compared with the raw materials, a synergistic improvement of strength and ductility is achieved in the Zr–Ti composite as a result of the layered gradient microstructure. Tension–compression asymmetry is observed in the Zr–Ti composites, which may be attributed to twinning and microvoids induced by unbalanced diffusion.

Key words: Zr–Ti layered structural material; diffusion annealing strengthening; tension–compression asymmetry yielding; ductility