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. σ_UTS of the synthesized TMCs increased gradually from 654MPa to 1138MPa when the volume fractions of hybrid TiC and TiB were raised from zero to theoretical value of 13.6vol%; 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.