With the increase in demand for high speed and efficient transport, there is a growing call for lightweight materials with high specific properties. Titanium matrix composites (TMCs) are one material of growing interest, whose properties make them a competitive replacement for many superalloys used in the aerospace industry. However, high cost, poor ductility, and the lack of a reliable manufacturing process have limited their application. In this study, we demonstrate the fabrication of high-performance titanium matrix composites reinforced with a network of high aspect ratio TiB nanowhiskers to overcome these challenges. A unique combination of fine BN nanopowder and a low-cost sintering method was employed. Ultralong, 40–50 μm TiB nanowhiskers with an aspect ratio of 500 have been produced from the in situ reaction between Ti and BN during slow heating/cooling, with temperatures at and below 1100 °C. As-sintered composites reached a hardness of 8.52 GPa, a reduced Young’s modulus of 152 GPa, and a yield strength of 1236.5 MPa, a 250% increase when compared to pure titanium as measured by nanoindentation. The improved mechanical properties were attributed to the ultrahigh aspect ratio of TiB, the low titanium grain size, and the near continuous network of TiB reinforcement. Slow heating/cooling allows for control of TiB formation to achieve the maximum aspect ratio as well as complete conversion of BN to TiB. In addition, the TiB network in the grain boundary acted to restrict Ti grain growth during manufacturing and improve the overall TMC properties. The proposed manufacturing method has great potential for the low-cost production of high performance TMCs.

Titanium and its alloys have been employed in the biomedical industry as implants and show promise for more broad applications because of their excellent mechanical properties and low density. However, high cost, poor wear properties, low hardness and associated side effects caused by leaching of alloy elements in some titanium alloys has been the bottleneck to their wide application. TiB reinforcement has shown promise as both a surface coating for Ti implants and also as a composite reinforcement phase. In this study, a low-cost TiB-reinforced alpha titanium matrix composite (TMC) is developed. The composite microstructure includes ultrahigh aspect ratio TiB nanowhiskers with a length up to 23 μm and aspect ratio of 400 and a low average Ti grain size. TiB nanowhiskers are formed in situ by the reaction between Ti and BN nanopowder. The TMC exhibited hardness of above 10.4 GPa, elastic modulus above 165 GPa and hardness to Young’s modulus ratio of 0.062 representing 304%, 170% and 180% increases in hardness, modulus and hardness to modulus ratio, respectively, when compared to commercially pure titanium. The TiB nanowhisker-reinforced TMC has good biocompatibility and shows excellent mechanical properties for biomedical implant applications.

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