Effect of High-Pressure Torsion on Structure and Microhardness of Ti/TiB Metal-Matrix Composite

Effect of high-pressure torsion (HPT) at 400 degrees C on microstructure and microhardness of a Ti/TiB metal-matrix composite was studied. The starting material was produced by spark plasma sintering of a mixture of a pure Ti and TiB2 (10 wt %) powders at 1000 degrees C. The microstructure evolution during HPT was associated with an increase in dislocation density and substructure development that resulted in a gradual microstructure refinement of the Ti matrix and shortening/redistribution of TiB whiskers. After five revolutions, a nanostructure with (sub) grain size of similar to 30 nm was produced in Ti matrix. The microhardness increased with strain attaining the value similar to 520 HV after five revolutions. The contribution of different hardening mechanisms into the hardness of the Ti/TiB metal-matrix composite was quantitatively analyzed.