Mg improves the distribution of Al2O3 nanoparticles in an Al matrix via solidification

Abstract

We report the effect of Mg addition on the distribution of a low content of Al2O3 nanoparticles in the Al matrix as well as the mechanical properties of the prepared nanocomposites. The results show that the average grain size was slightly smaller in nanocomposites with Mg than those without. The addition of Mg leads to complete dispersion and uniform distribution of Al2O3 nanoparticles in the Al matrix. The uniform distribution of Al2O3 nanoparticles is contrary to the view that most Al2O3 nanoparticles are pushed to the grain boundary with the low volume fraction of nanoparticles added into the metal melt. MgAl2O4 formed at the interfaces improved the interfacial wetting and bonding between nanoparticles and the Al matrix. The addition of magnesium leads to a significant increase in the elongation of nanocomposites. Orowan strengthening increased the yield strength and tensile strength of nanocomposites with Mg versus those without Mg. The tensile strength and yield strength of nanocomposites with Mg were 265 MPa and 206 MPa, respectively—an increase of approximately 29% and 51% versus Mg-free nanocomposites.