Strengthening of Aluminum by SiC, Al2O3 and MgO

The objective of this experimental investigation is to produce a metal matrix composite (MMC) using pure aluminum as a base material reinforced with one of the following ceramic additives each time (alumina Al2O3, silicon carbide SiC, and magnesium oxide MgO) with different volume fractions. Liquid state mixing technique was employed for the different constituent. Temperature was checked frequently while mixing using a thermocouple. Degasser was added to the content of the composite while mixing to minimize gas bubbles at the final cast.After melting and mixing, melts were poured in metallic mould then we got a cast from which specimens for various tests were prepared. Complete mixing between the Al matrix and the additives was checked by taking specimens from different parts from the cast (from the upper middle and the upper edge, and from the middle, then from the lower middle and lower edge then subjected to microscopic observation. Microstructure examination and microanalysis were carried out using optical microscope and scanning electron microscope equipped with energy dispersive x-ray analysis, moreover tensile mechanical properties were determined in each case.The addition of SiC, MgO Al2O3 particulates into the matrix alloy increased the yield strength, the ultimate tensile strength the hardness, decreased elongation (ductility) of the composites in comparison with those of the matrix. Increasing wt% of SiC, MgO Al2O3 increased their strengthening effect but SiC is the most effective strengthening particulates, for higher strength, hardness, grain size reduction. On the other hand, it decreases ductility toughness.