Abstract
The impact of 0.5 and 3 turns high-pressure torsion (HPT) as a severe plastic deformation technique on the microstructural evolution, crystalline texture, shear behavior, and microhardness distribution of an as-cast AZ80/1.5 vol.%TiO2 magnesium nanocomposite was investigated. The initial as-cast sample exhibited a microstructure characterized by large grains and an inhomogeneous structure, with an average grain size of 90 µm. However, after 3 turns HPT, a fine and homogeneous grain structure with an average size of 1.4 µm was obtained. By applying 0.5 and 3 turns HPT, the random texture of the as-cast sample was transformed to a semi-shear component. The mechanical properties were locally assessed using the shear punch test (SPT). The as-cast AZ80/TiO2 nanocomposite exhibited shear yield stress and ultimate shear strength of 121 and 130 MPa, respectively. After applying 3 turns of HPT, these values increased to 152 and 178 MPa, respectively. The strength enhancement was attributed to the finer grain size and basal texture on the analyzed surface. Meanwhile, the hardness increased by 60% as a result of the HPT process, which is consistent with the decrease in grain size and improved shear strength. By increasing the HPT turn from 0.5 to 3, the uniformity of the hardness distribution over the whole part of the tested disks was improved as a result of more homogeneous miscrostructure.