Effect of thermomechanical processing on microstructure and tensile properties of Al–20%Mg2Si–xCe composites

Due to its appealing properties, Al-Mg 2 Si composite is among the popular composites used in many industrial applications. The objective of this study is to address the combined effect of cerium (Ce) addition of different amounts (0, 0.3, 0.5, 0.8, and 1.0 wt. %) and hot extrusion on microstructure and tensile properties and fracture behaviour of Al–20%Mg 2 Si composites. Microstructure of the composites were analysed using optical microscopy, scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Mechanical property was examined using tensile testing. In addition, cooling curve thermal analysis (CCTA) was carried out to monitor the solidification behaviour of the fabricated composites. The results demonstrated that Ce addition, together with extrusion, refines Mg 2 Si particle’s size, altered their morphology, promotes the formation of Ce-rich intermetallic compounds, and enhances tensile strength and ductility. It is found that introducing Cerium in concentrations up to 0.8 wt.% together with hot extrusion resulted in a progressive decrease in the primary Mg 2 Si particle size from 46 μm to 23 μm and altering its morphology from dendritic to near spherical shape. Consequently, ultimate tensile strength (UTS), yield strength (YS) and elongation percentage (El%) escalated from 166 MPa to 247MPa, 55MPa to 74MPa and from 2.08% to 12.62% respectively with the addition of 0.8 wt. % Cerium and hot extrusion process. In extruded 0.8 wt.% Ce modified composite, stress concentration is revealed to be reduced, with enhanced ductility due to rounding of the primary Mg 2 Si particle edges which caused conversion from brittle to ductile mode of fracture.

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