Strength and ductility synergy of SiC reinforced aluminum matrix composites through interface replacement strategy

Introducing intragranular reinforcements plays an important role in improving the strength and ductility of composites. However, it is still a challenge to regulate the distribution of reinforcements in Al matrix composites. In the present work, the surface of nano-SiC_p coated by a thin layer of amorphous SiO₂ was realized through oxidation treatment to achieve interfacial replacement, which reduces the binding force between the particles by two orders of magnitude. This strategy realizes a uniform dispersion of the nanoparticles in the matrix. The results show that more than 60 % of the oxidized SiC particles (SiC_op) are distributed inside the grains, while the amount of the raw SiC_p without oxidation is only 35 %. The presence of an inter-diffusion amorphous interlayer improves the interface bonding between SiC_op and the aluminum matrix. Due to this unique structure design, the SiC_op/Al-11Si composites exhibit a simultaneous increase in strength and ductility. The yield strength, ultimate tensile strength and elongation to failure of 9 wt. % SiC_op/Al-11Si are 273.4 ± 4.6 MPa, 400.8 ± 6.9 MPa and 6.8 ± 0.4 %, respectively. Altogether, this study provides a simple and feasible method for fabricating strong and ductile SiC_p/Al matrix composites, and provides a conceptual framework for designing other ceramic particle-reinforced metal matrix composites.