Effects of temperature field and SiC nanoparticles on microstructure and mechanical properties of n-SiCp/Mg-9 %Al composites fabricated by ultrasonication-assisted semi-solid hot pressing of powder

Abstract

Abstract Mg-9 %Al magnesium matrix nanocomposites reinforced by 5 wt.% nanometre-sized SiC particles were synthesized via semi-solid powder hot pressing assisted by ultrasonication. The effect of the temperature field on the microstructure and tensile properties of the nanocomposites was systematically investigated. The distribution of the SiC nanoparticles, grain size, and morphology of the Mg17Al12 phase were found to be greatly affected by the hot-pressing temperature, resulting in strength and ductility first increasing and then decreasing with increasing hot-pressing temperatures. As the hot-pressing temperature increased to 510 °C, the nanocomposites consisted of hard SiC nanoparticles and isolated soft phases, and the SiC nanoparticles bonded well with the matrix without interfacial activity and exhibited the most uniform distribution in the nanocomposite. Moreover, compared to the Mg-9 %Al alloy, the nanocomposites exhibited significantly improved strength and excellent ductility both at room temperature and elevated temperature. The enhanced mechanical properties were attributed to the Orowan strengthening mechanism, the obvious grain boundary strengthening, and the load transfer effect.