Overcoming brittleness of high volume fraction Al/SiCp composites by controlling interface characteristics

• An effective and practical interfacial treatment method for the fabrication of high-fraction composites has been developed. • The strain at fracture of a 55 vol% Al/SiCp composite increased by 62.2% utilizing reinforcement surface treatment. • Interface modification increased the plasticity by changing the crack path from interface to fracture of the reinforcement. • By neutron diffraction, it was observed that the matrix metal was subjected to hydrostatic pressure during the compression. • Enhanced interface strength improves the high-temperature wear resistance by changing the wear behavior. Particle-reinforced metal matrix composites (MMCs) with high-volume-fraction of above 40% are highly attractive in the field of structural materials because they impart enhanced reinforcement properties to metals. However, high-volume-fraction MMCs are not widely used due to their brittleness. Therefore, overcoming the brittleness of the high-volume-fraction composites is the first step to disseminate the high-reinforcement-fraction composites. In this study, the interface bonding of 55 vol% Al/SiCp composites was strengthened by modifying the interface characteristics to achieve high plasticity of the high-volume-fraction composite. The interface bonding strengthening was conducted by thermal oxidation of SiCp reinforcement. The increased plasticity of the composites was observed as the 62.2% increased fracture strain in the compression test. The interface modification changed the crack path during a compression test from interface crack to reinforcement particle crack. To investigate the mechanism of interface modification, in-situ neutron diffraction experiments were performed under compression. When the plasticity is enhanced by the interface treatment, most fractures consist of reinforcement fractures rather than interface fractures. Therefore, it is confirmed that controlling the interface treatment is a key factor to improve the plasticity in high-volume-fraction composites. This work shed light on developing new composite material with high-volume-fraction reinforcement.