Hybrid effect of TiBw and TiCp on tensile properties of in situ titanium matrix composites

In order to study the hybrid effect of in situ TiB whisker (TiBw) and TiC particle (TiCp) on the tensile properties of titanium matrix composites (TMCs), TMCs with various TiBw/TiCp volume ratios of 4:1, 1:1 and 1:4 were prepared by reactive hot pressing of blended powders of Ti, B₄C, and graphite. Room tensile testing results exhibited that the composite with TiBw/TiCp volume ratio of 1:1 experienced an increase in the ultimate tensile strength of 25 and 50%, respectively, over the composite with ratio of 4:1 (based on Ti-B₄C) and pure Ti. The hybrid strengthening effect still existed at elevated temperature but it was not as obvious as that of room-temperature. Meanwhile, the ductility of the composites was decreased with decreasing TiBw content. The results suggest that the hybrid effect exists both at room and at elevated temperatures and it should be taken into account to prepare TMCs with good mechanical properties.