Direct Additive Manufacturing of Al2O3-TiCp Composite Ceramics by Laser Directed Energy Deposition

Al2O3-TiCp (AT) composites are frequently used as materials for metal cutting tools due to their superior mechanical properties. However, conventional sintering methods for AT materials have limitations in terms of energy consumption and cycle time. Therefore, in this study, direct additive manufacturing of AT composite ceramic materials was investigated using laser directed energy deposition technology. Effects of different TiCp ratios on the microstructure and mechanical properties of composite ceramic materials were explored. The results demonstrate that TiCp particles are uniformly distributed throughout the matrix of the fabricated samples, leading to refinement of Al2O3 grains. Stress induced by mismatch between the thermal expansion coefficients of TiCp and the Al2O3 matrix causes cracks to deflect and penetrates the particles, which consumes the crack extension energy and effectively suppresses the cracks in AT materials. Additionally, doping TiCp particles affects the molten pool by increasing the gas escape rate and improving the material density. However, high TiCp content aggravates the reaction with Al2O3 at high temperature, resulting in generation of gas and large pores in the composite material, which reduces the mechanical properties. Composites with TiCp mass fraction of 30% exhibit the best mechanical properties, with a relative density of 96.64%, microhardness and fracture toughness of 21.07 GPa and 4.29 MPa.m(1/2).