Fabrication, microstructure and mechanical properties of in situ formed particle reinforced titanium matrix composite.

The field of particulate reinforced titanium matrix composites (TMCs) has seen significant progress and breakthroughs over the last two decades. Among the particulate reinforced TMCs, Ti/TiB composites have been studied and well adopted in the industry. Despite many advantages, Ti/TiB composites, however, do not possess high wear resistance. Contrary to Ti/TiB composites, incorporation of Si 3 N 4 into the Ti matrix can significantly increase the wear resistance. This study makes use of both reinforcements (Ti/TiB composite as core material and Ti/Si3N 4 as shell material) to produce a high strength, high wear-resistant hybrid composite system. The resultant composites were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The results revealed complete decomposition of Si 3 N 4 reinforcement and the formation of needle-shaped TiB whiskers, indicating that in situ reaction occurred during the vacuum sintering of the powder compacts. All the composite samples had a high sintered density. The hardness of the composites increased with an increase in the mass fraction of Si 3 N 4. Tensile strength and tribological properties were determined and found to be dependent on the mass fraction of the reinforcements, respectively. The results show that by combining the two reinforcements, composite with a high-strength core and a high wear-resistant surface can be realized. • In situ titanium composites were successfully fabricated for potential core-shell applications • Dense composites were developed via press and sinter route • An increased weight fraction of Si 3 N 4 beyond 1 wt% result in excellent wear resistance [ABSTRACT FROM AUTHOR]