Investigation on corrosion behavior of the Al-B4C metal matrix composite in a mildly oxidizing aqueous environment

The corrosion behavior of Al-B4C (aluminum-boron carbide) metal matrix composites in a 0.5 M potassium sulfate (K2SO4) solution was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization methods. Optical and scanning electron microscopes as well as profilometry were used to study the surface morphology of the material before and after corrosion. Moreover, infrared reflectionabsorption spectroscopy (IRRAS) and x-ray photoelectron spectroscopy (XPS) were used to identify the corrosion products. It was observed that SO4 2- species did not induce pitting of the AA1100 (UNS A91100)-16 vol% B4C. In contrast, it was found that the Al-B4C composite was highly susceptible to pitting attacks by chloride ions, especially at the Al/B4C interfaces. The B4C particles showed a cathodic character with respect to the peripheral matrix, and both the IRRAS and XPS results showed that bayerite (Al[OH]3) was the main corrosion product. \ua9 2011, NACE International.Peer reviewed: YesNRC publication: Ye