Effects of SiC particle pretreatment and stirring parameters on the microstructure and mechanical properties of SiCp/Al–6.8Mg composites fabricated by semi-solid stirring technique

Al–6.8Mg aluminum composites reinforced by 10 vol.% SiC particle (10 vol.% SiCp/Al–6.8Mg) with homogeneous particle distribution and superior mechanical properties were successfully fabricated by semi-solid stirring technique. The effects of SiC particle pretreatment and stirring parameters on microstructure and mechanical properties of the composites were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and tensile tests. The results show that SiC particle pretreatment significantly improves the wettability and interfacial bonding strength between SiCp and Al–6.8Mg matrix, which further improves the homogeneity of SiC particle distribution and tensile properties of the composites. The optimal stirring parameters of 612 °C/500 rpm/30 min are exploited based on the SEM microstructure and tensile properties of the composites. The tensile strength of the composite fabricated by the optimal parameters is 344 MPa, which is 43.3% higher than that of the monolithic Al–6.8Mg alloy (240 MPa).

Research highlights▶ The pretreatment of SiCp significantly improve the wettability between SiCp and Al–6.8Mg alloy. ▶ The optimal stirring parameters of 612 °C/500 rpm/30 min are used to fabricate the composites. ▶ The tensile strength of the composite increased by 43.3% relative to that of Al–6.8Mg alloy.