Experimental studies and regression analysis on mechanical properties of MMCs based zinc-aluminium alloys with graphite particles reinforcement

Abstract

In recent years, zinc-aluminium (ZA) alloys have found increasing uses in several applications because these alloys exhibit a good combination of mechanical, physical and tribological properties along with low cost of fabrication. In order to further enhance some of the properties of non-ferrous alloys, many attempts have been made to produce MMCs with Al alloys, Mg alloys, Cu alloys and Ti alloys as the matrix materials. Literature on aluminum alloy composites suggests the effective use of graphite as a potent reinforcement. The absence of data on ZA alloys with graphite reinforcement was the stimulus for pursuing this systematic work. In this study, the results of the experimental investigation with varying graphite reinforcements on the mechanical properties of the popular ZA base alloys (viz., ZA8, ZA12 and ZA27) are reported. The casting trials were done using the stir casting technique. In all the cases studied, the UTS, YS and percentage elongation increased with increasing addition of graphite particles, while hardness decreases with graphite particles addition. ZA27 reinforced with 6% graphite exhibited the maximum improvement in UTS, YS, % E and least decrease in hardness. The lowest improvement in mechanical properties with graphite reinforcement was in the case of ZA8, while ZA12 showed an intermediate trend. Design of experiments (DOE) denotes the methodology of application of statistical techniques in experimentation. This has been attempted in this work, for the first time for the ZA alloy based composites. Proceeding further, multiple regression models have been worked out for the UTS, YS, %E, and BHN. Confirmation test results are in good agreement with the values predicted.