Microstructure and mechanical properties of P/M titanium matrix composites reinforced by in-situ synthesized TiC-TiB

Titanium matrix composites (TMCs) were prepared via reactive Ti-B4C system by powder metallurgy and hot extrusion route. The effect of the volume fraction of in-situ synthesized TiC particles and TiB whiskers on microstructure and mechanical behavior of TMCs were investigated. TiB whiskers showed favorable alignment oriented parallel to the deformation axis after hot extrusion; TiC particles and TiB whiskers distributed homogenously throughout the as-extruded composites. σUTS of the synthesized TMCs increased gradually from 654 MPa to 1138 MPa when the volume fractions of hybrid TiC and TiB were raised from zero to theoretical value of 13.6 vol%; the elongation decreased from 32.4% to 2.6% correspondingly. The strengthening effect of in-situ formed TiC-TiB hybrid reinforcements at room and elevated temperature was studied based on the load-transfer mechanism between the titanium matrix and TiC-TiB reinforcements. It was found that synergistic of the TiC particle and TiB whisker showed beneficial strengthening effect on mechanical properties of TMCs.