The preparation, microstructure, and performance of MoAlB-Si ceramic sintered from combustion-synthesized powder

To streamline the preparation process and improve the performance of the MoAlB phase, the technical potential of an ultra-fast combustion synthesis followed by hot pressing to prepare the MoAlB–Si ceramic was investigated. During the combustion process, the Si atoms occupied the Al positions, which forms a Mo(Al,Si)B solid solution phase. Si doping resulted in the effective grain refinement of the hot-pressed MoAlB-Si ceramic. The grain-refined and solid-solution-strengthened MoAlB-Si ceramic exhibits excellent mechanical properties with a compressive strength of 2.63 GPa, flexural strength of 650 MPa, fracture toughness of 7.26 MPa m^1/2, and Vickers hardness of 13.32 GPa. At elevated temperatures, a newly formed oxidation-derived dense and continuous layer on the surface prevents the inward diffusion of oxygen and the volatilisation of oxidation products, indicating good oxidation resistance of the MoAlB-Si ceramic.