EFFECTS OF HOT EXTRUSION RATIO ON MICROSTRUCTURE OF Al – 25 WT.%Mg2Si IN-SITU METAL MATRIX COMPOSITE

This study was undertaken to investigate the effects of hot extrusion ratio on the microstructure of cast aluminum metal matrix composite (MMC) containing 25 wt.% coarse Mg2Siprimary particles. Different extrusion ratios (6:1, 12:1 and 18:1) were applied on the small cast composite ingots at 520 ºC. Microstructural data were assessed by the use of optical microscope (OM) equipped with quantitative data analyzer and scanning electron microscope (SEM). The results showed that hot extrusion with the ratio of 18:1 has the maximum effect on the size reduction of Mg2Si particles. Particle fracturing during hot extrusion changes the size of coarse Mg2Si particles from 92 μm to 24 μm, which shows about 75% reduction. Due to high stress-concentrated areas around Mg2Si particles, reduction in the size of primary Mg2Si particles reduces the stressconcentrated areas and results in enhancing mechanical properties.

کلیدواژه ها:

Metal matrix composite (MMC) ، Mg2Si particles ، Microstructure ، Hot extrusion ratio