Corrosion behaviour of aluminium matrix composites containing silicon carbide particles

An examination of the pitting attack in two aluminium matrix composites (1050 and 2124) each reinforced with varying fractions (0-30 wt. %) of silicon carbide particles (SiCp) in the size range 3-40 mu m has been made in 1 N NaCl solution. It has been demonstrated that the existence of pores and crevices at SiCp/matrix interfaces strongly influences pit initiation. This is further aided by the cracking of large SiCp greater than or equal to 20 mu m, during processing. The presence of theta(CuAl2) and S(CuMgAl2) precipitates in 2124-SiCp composite also promotes pitting attack at SiCp-matrix and intermetallic-matrix interfaces.