Microstructure and mechanical properties of Al/SiC surface composite with different volume fractions using friction stir process

Abstract

Friction stir processing (FSP) was used to produce Al/SiC composites on the surface of Al 1050 sheets. SiC particles of 1 µm size were added on the Al sheet surface inside grooves with different sizes in order to obtain different composite volume fractions. FSP was applied with a square shape tool rotating at 1500 rpm and with a feed rate of 116 mm/min. The effect of SiC volume fraction on microstructure, and mechanical properties was investigated and the results were compared with samples treated by FSP but without SiC reinforcement. Different SiC volume fractions were obtained ranging from 7% to 16% depending on the groove size. Optical microscopic analysis (OM) in collaboration with scanning electron microscope (SEM) were used to fully discuss the microstructural changes within each sample. Mechanical properties were investigated through microhardness and tension test (including yield strength, ultimate tensile strength and percentage elongation). The results show significant improvement in microstructure changes in the FSPed composites, where equiaxed and refined grains structure were obtained due to the effect of the severe plastic deformation and continuous dynamic recrystallization caused by FSP compared to the elongated and coarse grains of the base metal. Microhardness and strength of the FSPed composites improved up to 112% and 9.7%, respectively compared to the as-received material.