Mechanical Behaviour and Morphology of A356/SiC Nanocomposites Using Stir Casting

Abstract

In this research an attempt has been made to explore the experimental investigation of A356/SiC nanocomposites using two step stir casting process. A356 alloy ingot was selected for the matrix and the reinforcement (aluminium fine powder (99.9%) plus nano size SiC mechanically forged by using ball mill at 100 rpm for duration of 10 hours). Ball milling process enhances the wettability of the particles. Reinforcement was varied from 1% to 5% with a step of 1% by weight. The stirring process was carried out at 500±50 rpm with stirring duration 10 minutes in two steps. The melt composites were poured at 680±20° C into the die to fabricate the composites. In this process of fabrication, less oxides/segregations were depicted. Tensile strengths of fabricated composites were evaluated by using UTM and toughness was calculated from area under stress-strain curve. To identify the involvement and presence of the nanoreinforcement into the matrix alloy (A356), fractured surfaces of the fabricated nanocomposites were examined using SEM and EDX. Tensile test results have shown the fracture mechanism and enhanced mechanical properties with the addition of forged nanoreinforcements. Yield tensile strength (YTS) and ultimate tensile strength (UTS) of A356 parent alloy found as 212.76 MPa and 219.90 MPa respectively. The improvement of 41% in YTS and 45% in UTS in case of A356/SiC nanocomposites were investigated. Decrease in % elongation and toughness with increase in forged nanoreinforcement were predicted. Proper distribution of reinforcement was attributed by SEM micrographs. EDX spectrum disclosed the presence of the constituents in the parent alloy (A356) and stir cast nanocomposites.