Synthesis and characterization of an in-situ magnesium-based cast nano composite via nano-sio2 additions to the melt

Abstract

In this study, AZ91C magnesium matrix in-situ nano-composites reinforced with oxide particles were produced by the addition of 2 % of mass fractions of silica nanoparticles to the melt using the stir-casting method. For this purpose, nano-silica powder was mixed in molten AZ91C by a special procedure and stirred for 15 min at 750 °C and cast in a preheated die at 720 °C. Control samples were also cast under the same conditions. Improved microstructure, reduced porosity and increased hardness, tensile strength and yield strength of the composite sample were revealed by microstructural and mechanical investigations. The hardness, yield strength and tensile strength values increased from 65 BHN, 82 MPa and 165 MPa for the monolithic samples to 77 BHN, 97 MPa and 175 MPa for the in-situ formed cast composites. Microstructural and EDS analyses suggested the in-situ formation of Al2O3, MgAl2O4 and MgO oxide particles by in-situ reaction of the Al, Mg and SiO2 in the melt.