Review of Advances in High-Pressure Torsion of Titanium and Ti-Based Materials (Alloys, Intermetallics, Oxides and High-Entropy Compounds)

Titanium and Ti-based materials are advanced materials that have found applications across various fields of science and engineering. Over the past three decades, significant efforts have been made to employ severe plastic deformation (SPD) via the high-pressure torsion (HPT) method on Ti-based materials. These efforts aim to achieve ultrafine grains with a high density of lattice defects, control phase transformations, and synthesize new compounds. Pure titanium, and Ti-containing alloys, intermetallics, ceramics and composites have been processed by HPT to enhance mechanical and functional properties. These properties include high hardness, high strength combined with plasticity, biocompatibility, superconductivity, dielectric performance, photocatalysis, electrocatalysis and photovoltaic capabilities. Additionally, the synthesis of new high-entropy alloys and ceramics via HPT has emerged as a promising direction, contributing to various disciplines such as photocatalysis, biomedical devices and hydrogen storage. This article provides a brief overview of the SPD concept and the HPT method, followed by a summary of recent advances in the HPT processing of Ti-based materials.