Deformation mechanism of multilayer gradient ultrafine grained titanium

Ultrafine grained titanium with multilayer and gradient structure was designed and prepared by combining cold rolling and surface mechanical wear treatment. The mechanical properties of the prepared ultrafine grained titanium were tested. The microstructure was observed by scanning electron microscopy, and the deformation mechanism of the material was studied in detail by transmission electron microscopy. The results show that each layer had its own specific deformation and failure mechanism. The deformation mechanism included a large number of shear banding of amorphous nanocrystalline mixed layer, grain boundary induced deformation of nanocrystalline layer and local shear of ultrafine grain core. The gradient at the connection between layers reduced the degree of interface damage, increased the crack arrest effect, and improved the contact bearing capacity. This complex plastic deformation improved the strength and work hardening properties of multilayer gradient titanium.