Effects of Mo on microstructure and properties of TiC/Al composites

In order to improve the reinforcement of TiC on Al matrix material, the element of Mo had been add into the 6A02 (LD2) aluminum based alloy to reduce the size of in situ TiC particulates. Microstructure of as-cast piece and rolled piece had been observed, and tensile properties and wear properties had been tested. The results show that TiC particulates can act as heterogeneous nucleation sites, which results in refined microstructure. Either at room temperature or at high temperature, the ultimate tensile strength (UTS) and yield strength of the composites increase with addition of TiC particulates. Wear resistance of the TiC reinforced composites is improved remarkably, especially when the contact load is developed. 1.0wt% Mo additive to the alloy improves the wettability of Al melt on TiC particles. Moreover, the distribution of TiC particles in the base alloy becomes more uniform and the size of TiC is reduced to 0.5 μm in diameter, which leads to the development of mechanical properties and wear resistance. However, the excess of Mo addition causes the brittle Al5Mo precipitate in the microstructure, and then the composites exhibit the worsening mechanical properties and wear property.