Investigating physical properties of ZX51-Al2O3 magnesium matrix composite fabricated by stir casting and hot extrusion

In this paper, ZX51-xAl2O3 (x=0, 2.25, 4.5, and 6.75 vol%) magnesium matrix composites were fabricated by stir casting and then were hot extruded at 300, 350, and 400°C. After precise measuring of density based on Archimedes’ principle, physical properties of produced composites including apparent density, relative density, and volume percentage of porosity were investigated and also were statistically analyzed with the aid of Regression. The results showed that the apparent density and volume percentage of the porosity increase linearly and quadratically respectively for both the as-cast and extruded composites, while the relative density of the composites decreases by a second-order polynomial function when the amount of particle reinforcements increases. However, for all volume percentages of the reinforcement, the apparent and relative densities of the extruded composites were higher than those of the as-cast counterparts. In contrast, an opposite behaviour was observed for volume percentage of porosity; indicating of decreasing porosity content in consequence of extrusion processing. Contrary to serious effects of alumina particles volume percentage, physical properties of the extruded composites seemingly behaved independent of extrusion temperature.