Mechanical properties and wear resistance of semisolid cast Al2O3 nano reinforced hypo and hyper-eutectic Al–Si composites

Abstract

The present investigation studies the prospects of using nanoparticles as reinforcement ceramic powders to gain improved performance of hypo and hyper eutectic Al cast alloys. A series of castings were prepared using A356 and A390 as the matrix alloy and alumina nano-powder in 40 nm size as the reinforcement. The nanoparticles were added to the molten slurries with stirring with different fraction ratios ranging from (0, 1, 2 and 4 wt%) in the mushy zone using a constant stirring time for one minute. To evaluate the results, the alloys were further characterized by various tribological and mechanical characterization methods. The results showed higher strength values with improved ductility compared to the monolithic alloys under the same casting conditions. The results also showed improvement in the wear resistance of the nano-reinforced alloys. The scanning electron microscopy of the fracture surface and the wear surface revealed the presence of nanoparticles in the interdendritic spacing and this confirmed with EDX analysis of these particles. The data obtained from the experimental work in this study together with previous published work by the authors were statistically analyzed using analysis of variance (ANOVA) to define the significant factors on both ultimate tensile strength and ductility and their level of confidence, using the orthogonal array L8. Response surface methodology (RSM) was used to build a model relating the type of matrix and nanoparticles addition to the ultimate tensile strength (UTS). The results have shown that the percent of the nanoparticles additions have a significant effect on the tensile properties of the alloys.