Hot rolling effects on as-cast aluminum matrix nanocomposites reinforced by nano-sized ceramic powders

In this study, aluminum matrix nanocomposites were produced by the semi-solid stir casting process. For this purpose, alumina and SiC nanocomposite superstructures were prepared using ball-milling of alumina and SiC nanopowders with micron-sized copper powders, respectively, to reinforce A356 aluminum alloy. In fact, copper powders were used as a carrier agent of ceramic nano-powders to increase their wettability by the semi-solid melt. Afterward, ascast nanocomposites were exposed to hot rolling process to find the effects of high temperature deformation on their microstructure and mechanical properties. The experimental results indicated that as-cast products contained various types of pores as well as cracks. Also, severe agglomeration of nanopowders was detected in the as-cast products, showing that the copper presence could not be completely effective to avoid agglomeration and poor wettability of nano ceramic powders. It was found that the hot rolling process reduced the amounts of pores and lead to a better dispersion of the nano ceramic clusters with improved mechanical properties for the hot-deformed products. In addition, it was also shown that the type of nano ceramics did not affect the performance of the hot rolling process.