Advances in bulk TiB2-based composites: Densification and toughening

TiB2 based materials have attracted extensive attention due to its considerable hardness and elastic modulus, excellent wear/ corrosion resistance as well as exceptional electrical/ thermal conductivity. The potential structural and functional applications of TiB2 based materials include reentry vehicles, cutting tools, thermal insulation boards, new energy batteries, ballistic protection high temperature nuclear reactors. However, the poor densification together with inferior fracture toughness dramatically limited the practical application of TiB2. Herein, we critically survey, summarize, and discuss the recent advances on preparation and mechanical properties of TiB2-based materials, focusing on the current understanding of densification and toughening strategies and mechanisms. Borrowing the concept of cemented carbide, cemented TiB2 is proposed in this review, highlighting the different binder phase on improving the densification of TiB2, including metal, intermetallic, ceramic and high entropy alloy. Subsequently, through discussing the factors influencing the efficiency of toughening TiB2, we determine and compare various toughening approaches on TiB2. Furthermore, the challenges and prospects of high performance TiB2 for future scientific researches and practical possibilities are also briefly summarized. We believe a thorough summary of the densification and toughening mechanisms will significantly contribute to the development of dense, strong and tough TiB2 materials in a much more efficient way, advancing them for further wide applications.