Corrosion resistance and tribological behavior of particles reinforced AZ31 magnesium matrix composites developed by friction stir processing

Abstract

The influences of different compositions of the reinforcement particles on phase compositions, microstructure characteristics, corrosion resistance, and tribological behavior of the AZ31 magnesium matrix composites (MMCs) were investigated. The defects-free AZ31 MMCs reinforced by Al, Al–Si and Al–SiC composite particles were prepared using friction stir processing (FSP). The phase composition of the MMCs is the same as that of the as-received AZ31 alloy and still consists of α-Mg solid solution and β-Al12Mg17 intermetallic. In addition to an obvious decrease in the average grain sizes, the sizes and distributions of the β-Al12Mg17 intermetallics in the MMCs are also significantly decreased and homogenized. The MMCs reinforced by Al–SiC composite particles exhibit maximum self-corrosion potential, while the MMCs reinforced by Al–Si particles present minimum self-corrosion current. The maximum self-corrosion potential and minimum self-corrosion current of the MMCs are −1.19 V and 4.37 × 10−5 A, respectively. In addition to an obvious enhancement in mean microhardness, the average friction coefficients of all the particles reinforced MMCs are higher than that of the AZ31 alloy, but the mass loss of the Al–Si composite particles reinforced MMCs is less than that of the AZ31 alloy. The wear mechanism of the AZ31 alloy is severe abrasion and adhesion, while the MMCs reinforced by Al–Si particles are mild abrasion.