Mechanical Properties and Localized Corrosion Behavior of Powder Metallaurgical Whisker Rainforced Aluminium Metal Matrix Composites

Abstract

The high strength and stiffness, lightness and low coefficient of thermal expansion make metal matrix compositions attractive materials for a diverse range of applications including aerospace, automotive, medical and sports equipment. In this study, the mechanical properties and corrosion behavior of whisker reinforced pure aluminum matrix composites produced by powder metallurgy technique were investigated by measurement of tensile and electrochemical properties in conjunction with their microstructures. The tensile strength and elongation of the composites reinforced with Al borate and TiO₂ whiskers were nearly equal to those of SiC whisker reinforced composite. The reactivities of Al borate and SiC whiskers with pure Al were lower than that of TiO₂ whiskers. The interfacial reactants act as anchors to enhance the cohesive force between matrix and fillers. The oxides whisker reinforced composites had more noble pitting potential compared to SiC whisker. Especially, TiO₂ indicated the most noble pitting potential. On the corroded surface of TiO₂ whisker reinforced composite, some precipitation products were found in the vicinity of whiskers. This is explained by the fact that the reactivity of whiskers with pure aluminum is different for the each combination. Therefore, the susceptibility of pitting corrosion depends on the formation ability of galvanic couple.