Low temperature failure of bulk nanostructured titanium processed by ECAP

Low temperature yield stress and the failure nanostructured titanium of commercial purity produced by severe plastic deformation were analysed. The mechanical properties for specimens with average grain size 15 mu m, 0.3 mu m and 0.1 mu m were studied under uniaxial compression with strain rate 4 x 10(-4) s(-1) at temperatures 300, 77 and 4.2 K. The failure mechanism was ductile fracture with a preceding formation of an intense shear band. Fractographic analysis revealed "vein" patterns observed at all shear failure surfaces. In a couple of aspects the micromechanism of the shear failure in nanostructured titanium is similar to that in bulk amorphous metallic glasses.