The effect of Na addition on the microstructure and tensile properties of Al-20 wt.% Mg2Si MMC

The cast unmodified and Na-modified Al–20 wt.%Mg2Si MMC was made and characterized by optical microscope and SEM. The results depicted that the addition of 1.0 wt.% Na to the MMC changes the morphology of primary Mg2Si particles from irregular or dendritic to polyhedral (often cubic) shapes and decreases its average size from ~120 μm to ~47 μm. Further results also depicted that the morphology of the eutectic Mg2Si phase alters from lamellar to mainly dot-like. Tensile tests revealed improvement of UTS and elongation values from 131 MPa and 1.1 %in unmodified to 152 MPa and 2.2 % in Na modified sample respectively. Fracture surface examinations revealed a transition from brittle fracture mode in as-cast unmodified composite to rather ductile in Na-modified specimens

کلیدواژه ها:

Metal matrix composite ، Modification ، Microstructure ، Tensile properties ، Casting