Pinning effect of in-situ TiC_p and TiB_w on the grain size and room temperature strength of (TiC + TiB)/Ti composites

(TiC_p + TiB_w)/Ti composite was firstly prepared by spark plasma sintering (SPS) and hot extrusion from Ti-B4C system, and then isothermally heat treated at 400–800 °C for 24 h to study the pinning effect of the in situ formed reinforcements. Microstructure and phase composition was investigated by SEM, XRD and TEM, variation of the grain size of Ti matrix was studied by EBSD analysis, and room temperature strength was also measured after different heat treatments. Results show that, comparing with pure Ti materials, both the grain size of Ti matrix and the room temperature strength of the composite almost keep stable after heat treatments, suggesting the pinning effect of in situ formed TiC_p and TiB_w is effective to suppress the growth of Ti matrix grains during heat treatments.