Microstructures and high-temperature oxidation behavior of MoSi2-MoAlB composites

In this study, MoAlB was introduced as a reactive precursor in MoSi 2 -based ceramics. During spark plasma sintering, MoAlB underwent in-situ decomposition, forming MoB and Al 2 O 3 phases. These phases were distributed uniformly within the MoSi 2 matrix as reinforcing phases. This resulted in significant improvements in hardness and toughness, with the peak flexural strength obtained for 10   vol% MoAlB addition. Oxidation tests from 900-1500 ℃ revealed a temperature-dependent oxidation behavior. At 1500 ℃, volatilization of MoO 3 and B 2 O 3 destabilized the oxide scale, while the 5   vol% MoAlB composite offered excellent protection at intermediate temperatures (900-1200 ℃). The formation of a stable SiO 2 -B 2 O 3 -Al 2 O 3 self-healing glass provided effective protection in this critical temperature range. These findings demonstrate MoAlB’s effectiveness in designing MoSi 2 -based ceramics for intermediate temperature applications.