The effect of severe plastic deformation on the microstructure and mechanical properties of (TiB+TiC) reinforced titanium matrix composites

Abstract

Equal-channel angular pressing (ECAP) was successfully applied to in-situ synthesized particulate reinforced titanium matrix composites. The results prove that the ultrafine-grained structure can be effectively obtained in the titanium matrix composite by ECAP at different temperatures and passes. Formation of homogenous TiB and TiC particles with ultrafine grains and sub-grains were obtained after 4 ECAP passes, which indicates that the reinforcement-induced ultrafine grains. The lamellar α phases are also twisted obviously due to the shear stress, which can reduce the average thickness of lamellar α phases to less than 1μm. After ECAP at relatively low temperature, dislocation pile-ups, dislocation tangling and plenty of cell structures with size of about 500nm can be observed in the matrix. While many newly formed ultrafine grains with clear grain boundaries and size of 100~500 nanometers have formed. The tensile test results show that the yield strength is improved by ECAP pressing and saturate after 4 ECAP passes to a value of 1150MPa, and the ductility is much higher compared with the first ECAP pass.