Strengthening behavior of in situ-synthesized (TiC-TiB)/Ti composites by powder metallurgy and hot extrusion

Titanium matrix composites (TMCs) reinforced with in situ-formed TiC particles and TiB whiskers were prepared by reacting titanium and B4C via powder metallurgy and hot extrusion. The effect of the in situ-formed TiC-TiB hybrid reinforcements on the microstructure and mechanical behavior of the TMCs was investigated. TiB whiskers exhibited favorable alignment, orienting parallel to the deformation axis after hot extrusion, while TiC particles and TiB whiskers were distributed homogenously throughout the extruded composites. The synthesized TMCs with a 13.6% volume fraction of TiC-TiB hybrid reinforcements presented a sigma(UTS) of 1138 MPa, representing a 74% improvement compared to pure titanium, and retained an acceptable elongation of 2.6%. The synergistic strengthening effect of TiC particles and TiB whiskers was investigated via in situ tensile observations based on the load-transfer mechanism between the titanium matrix and TiC-TiB reinforcements. (C) 2016 Elsevier Ltd. All rights reserved.