Nano-Ti5Si3 leading to enhancement of oxidation resistance

Highlights: • Nano-Ti₅Si₃ led to remarkable enhancement of oxidation resistance of composites. • The oxidation rate of composites decreased with increasing Ti₅Si₃ fractions. • Nano-Ti₅Si₃ was beneficial to forming a scale of mixed Al₂O₃ and SiO₂. • Nano-Ti₅Si₃ could lead to refinement of TiO₂ particles. • Oxide scale was fastened by hierarchical microstructure. - Abstract: Nano-Ti₅Si₃ particles were formed via solution and precipitation, which drastically increased mechanical properties of (Ti₅Si₃+TiBw)/Ti6Al4V composites. In the present work, compared with Ti6Al4V alloy at 700 and 800 °C, nano-Ti₅Si₃ particles led to remarkable enhancement of oxidation resistance, which increased with increasing Ti₅Si₃ fractions. The contributions of nano-Ti₅Si₃ particles were in two aspects: 1) were beneficial to forming dense and thin scale of mixed Al₂O₃ and SiO₂, which suppressed oxygen from permeating into matrix; 2) resulted in refinement of TiO₂ particles, which could enhance the toughness and relative density of oxide scale. The two-level hierarchical microstructure also stabilized oxide scale.