Microstructure and mechanical behavior of magnesium rare earth alloy nanocomposite fabricated by hybrid casting method

Abstract The metal matrix nanocomposites (MMNC) were fabricated using matrix material - rare earth magnesium (ZE41) alloy and beta silicon carbide nanoparticles as reinforcements. It was successfully developed by using a hybrid casting method, which included a double stirring as well as ultrasonication process. The reinforcing material is 0.75 wt% of beta-silicon carbide nanoparticles (β-SiCp) with the particle size ranging from 45 to 60 nm, has achieved even spread throughout the matrix. The base and ZE41/0.75 wt% SiC MMNC were direct aged at T5 heat treatment condition. The samples were material characterized using an optical microscopy (OM) and a field emission scanning electron microscope (FESEM). The MMNC showed 23.93% improvement in ultimate tensile strength (UTS) values when compared with as-cast monolithic material and the MMNC heat treated by T5 condition showed 15.10% improvement in the UTS values when compared to the base ZE41 treated with T5 condition. The grain size reduction of composite was evident in the optical micrographs, which contributed in the increase in tensile strength. The SEM analysis on fractured surfaces revealed that the crack initiation was from the matrix reinforcement interface and the mode of failure in the composite was brittle. The effect of double stir ultrasonication for successfully fabricating the MMNC and comparing it with the base alloy was the main aim of this work.