Microstructural characterization, tribological and corrosion behavior of AA7075-TiC composites.

Aluminum alloys are the potential materials in the automobile and aerospace sectors due to their lower density, easy forming and excellent corrosion resistance. The demand of high strength-to-weight ratio materials in structural applications needs the engineering industries to seek aluminum alloy with new versions of hard and brittle ceramic particles. The microstructure, hardness, wear and corrosion behaviors of AA7075 composites with 2.5wt.% and 5wt.% TiC particles were studied. Microscopic analysis is evident that the transformation of the strong dendritic morphology to non-dendritic morphology on the incorporation of TiC into AA7075. Furthermore, the precipitation of the second-phase compounds such as Al2CuMg, Al2Cu and Fe-rich Al6(Cu, Fe)/Al7Cu2Fe) is promoted by TiC particles at inter- and intra-dendritic regions. Accordingly, the hardness of composites is improved by grain boundary strengthening and particulate strengthening mechanisms. Both coefficient of friction and wear rate have an inverse relation with TiC concentration. The base alloy without TiC shows adhesive-type wear-induced deformation due to the formation of an oxide film, while composite samples exhibit a mechanically mixed layer and abrasive-type wear behavior. Composite samples shows a higher corrosion rate due to the presence of numerous precipitates which promote pitting corrosion. [ABSTRACT FROM AUTHOR]