Formation of Si nanoparticle in Al matrix for Al-7wt.%Si alloy during complex shear flow casting

Highlights: • Al-7wt.%Si alloy was produced by using complex shear flow casting method. • Si nanoparticles form in α-Al at graphite mould cooling rate. • There is a semi-coherent interface between Si nanoparticle and Al matrix. • Growing α-Al captures Al-Si or Si atomic clusters during shear-assisted casting. Al-7wt.%Si alloy was produced by applying complex shearing to the liquid melt during graphite mould casting. Microstructure was analyzed with optical microscope (OM), scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM). Results show that Si nanoparticles, which can only be conventionally obtained by melt spinning technique for cast Al-Si alloy, are embedded in Al matrix. There is a cubic to cubic orientation relationship (OR) and a semi-coherent interface between Si nanoparticle and Al matrix. Formation mechanism of Si nanoparticles has been discussed.