Microstructure, thermal and mechanical response of AZ51/Al2O3 nanocomposite with 2 wt.% Ca addition

Abstract

In the present study, new AZ51/Al2O3–2Ca magnesium nanocomposite was successfully synthesized by simultaneously adding 2wt.% aluminum, 2wt.% Ca and 1.5vol.% nanosized Al2O3 (50nm) into AZ31 matrix using a disintegrated melt deposition (DMD) technique. AZ51/Al2O3 nanocomposite was developed following the same processing route except adding Ca. Composite samples were then subsequently hot extruded at 400°C and characterized. Microstructural characterization studies revealed equiaxed grain size, reasonably uniform distribution of intermetallics and nanoparticulates in the matrix and minimal porosity. Results also showed that the addition of Ca into AZ51/Al2O3 nanocomposite helped to reduce the average grain size and introduced (Mg,Al)2Ca second phase. Physical properties characterization revealed that addition of Ca reduced the coefficient of thermal expansion (CTE) when compared to Ca free nanocomposite. Ca addition also assisted in improving overall mechanical properties including microhardness, 0.2% yield strength, ultimate tensile strength, and work of fracture while the ductility was compromised.