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Aluminum borate whisker (ABO w ) and silicon carbide particle (SiC p ) hybrid reinforced 6061Al matrix composites ((ABO w +SiC p )/6061Al) were fabricated by semi-solid mechanical stirring technique with different stirring temperatures and different stirring time. The influence of stirring parameters on microstructure and mechanical properties of the composites was investigated using scanning electron microscopy (SEM), X-ray diffractometry (XRD), transmission electron microscopy (TEM) and tensile tests. The results reveal that the homogeneity of reinforcement and tensile properties increase with decreasing the stirring temperature and increasing the stirring time. The optimal stirring parameters of 640°C and 30 min are exploited based on the microstructure observation and tensile properties of the composites.

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).

10% (volume fraction) SiC(subscript p)/Al-Mg composites with different Mg contents were successfully fabricated by semi-solid mechanical stirring techruque under optimum processing conditions. Effects of Mg content on microstructure and mechanical properties were studied by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The results indicate that SiC particles disperse homogeneously in Al-Mg matrix and interfacial reaction between Al matrix and SiC particles is effectively controlled. Distribution of SiC(subscript p) reinforcement and interfacial bonding are improved by adding Mg. Additionally, the mechanical properties of composites are remarkably improved with the Mg content increasing.

6061Al matrix composites reinforced by ZnO-coated Al 18 B 4 O 33 whiskers were fabricated by a semi-solid mechanical stirring technique. The effects of ZnO coating on interfacial reaction between whiskers and matrix and the tensile properties of the composites were investigated. Tensile tests on composites were performed at room temperature, and microstructures were observed by scanning electron microscopy (SEM). The results show that the surface treatment of whiskers could reduce interfacial reaction effectively, improve the wettability between whiskers and matrix and enhance the tensile properties of the composites obviously. In addition, semi-solid stirring parameters were also under preliminary study. The stirring parameters were determined by the distribution of whiskers in the composites. The composites with homogeneously distributed whiskers were fabricated by semi-solid stirring at 610 °C for 30 min.