Effect of C Addition Ratio on the Characteristics of TiC–Ti Composites Synthesized via Mechanical Alloying/Spark Plasma Sintering Using Their Elemental Powders for Sustainable Materials

WC–Co alloys, WC–Ni alloys, and TiC–Ni cermets are composite materials widely used in industrial applications because of their exceptional hardness, wear resistance, and durability. For these systems, WC, Co, and Ni are used as the raw materials. However, owing to their rarity and the instability of their supply, the development of alternative materials is underway to reduce their usage. TiC-based cermet is considered a promising alternative material. To replace conventional cemented carbide, a TiC–Ti composite material was synthesized via reactive milling and sintering using elemental Ti and C powders as the raw materials. The effect of C addition ratio on the properties of TiC–Ti composite material was investigated. The results indicate that when 20 and 25 mol% C were added, TiC gradually synthesized during milling using a planetary ball mill, whereas when 28 and 32 mol% C were added, the TiC phase was rapidly synthesized via a mechanically induced self-propagating reaction after a certain milling time. After spark plasma sintering at 1273 K, for the sintered compacts of 20 and 25 mol% C, the Ti phase was not finely dispersed, but was dispersed as large flattened grains of measuring approximately several tens of micrometers in size. However, for the sintered compacts of 28 and 32 mol% C, fine TiC particles with sizes of ≤3 μm were dispersed, and Ti was distributed in the gaps between them. A TiC–Ti composite containing 28 mol% C exhibited a Vickers hardness of approximately 850 Hv and a transverse rupture strength of 730 MPa which showed a similar level compared with the TiC–Ni system cermets. This material does not use rare metals, which are in limited supply, as the raw materials and has the potential to replace conventional composite materials such as WC–Co and WC–Ni alloys and TiC–Ni cermets. The material developed in this study is expected to minimize the use of rare elements like W, Co, and Ni, thereby making effective use of limited resources.