Fabricating Surface Composite by Friction Stir Brazing SiC p /A356 Composite Sheet onto Monolithic Al Plate in Air

For improving the wear resistance of soft Al substrate by fabricating surface composite, commercial Al metal matrix composite (MMC) SiC p /A356 sheet was cladded onto 1060 Al substrate by friction stir brazing (FSB) process, in which a pinless tool and Zn solder were used to avoid pin wear and to extend bonded width. The MMC/Al (top/bottom) configuration exhibited intimately contacted interface, Al-Zn bond seam reinforced by SiC particles and higher shear strength (70 MPa) due to sufficient dissolution with the aid of torquing action directly on the MMC sheet from the large rotating shoulder. For Al/MMC configuration, excessive softening of the top 1060 Al and indirect micro-shearing on the bottom SiC p /A356 resulted in excessive expulsion of molten Zn, insufficient dissolution, poor wettability and lower shear strength (35 MPa). FSB was able to produce a surface composite layer with large width up to shoulder diameter in air.