The role of Metal-Matrix Composite development During Friction Stir Welding of Aluminum to Brass in Weld Characteristics

The present research aims to investigate the development of brass reinforced aluminum composites during dissimilar friction stir welding of brass and aluminum. Moreover, to probe the effect of such a metal matrix composite on its bed, the cross-sectional properties of joint area are studied in two aspects of corrosion behavior and hardness distribution. Microstructural investigations through optical and electron microscopy show development of lamellar composites within the top site of the stir zone and aluminum surface. The measured iso-hardness contours indicate that evolved composite structures increase the cross-sectional hardness of aluminum locally. Also, the electrochemical assessment of joint area suggests that Al/Br composite structure plays an accelerative role in deterioration of cross-sectional corrosion resistance of aluminum through obstructing passivation and forming microgalvanic cells, where cathodic brass reinforcements intensify the corrosion of anodic aluminum matrix.