Effect of Mn addition on the micromechanical response and failure of Al-12.6Si alloy using actual microstructure based RVE model

Abstract

Eutectic Al-12.6Si alloy has been developed with and without Mn addition through the gravity casting method. Microstructure, mechanical properties, behavior of deformation, micromechanical response and failure propagation subjected to tension have been investigated. The representative volume elements (RVEs) technique and the deformation plasticity model (Ramberg-Osgood) have been employed to understand the effects of microstructure morphology on the micromechanical response and failure initiation under tension. It has been found that the Mn addition effectively modifies the Al-12.6Si alloy’s microstructure morphology, as an effect mechanical properties improved. Additionally, the alloy has a combination of brittle and ductile fracture modes under tension. The finite element analysis reveals that the stress and strain distribution (micromechanical response) and deformation behaviour of simulated Al-12.6Si Alloy RVEs change with changing Mn concentration in the alloy. Both the primary and eutectic Si phase and Al6Mn phase shared maximum load during tensile deformation. The primary mode of failure would be initiated by breaking of eutectic silicon flakes and unmodified primary Si particles and Al6Mn intermetallic. Both the Si particle's sharp corners and Al and Si phase interface are found as the preferable crack initiation site. Additionally, void initiation takes place at the narrow Al phase region in the microstructure. Eutectic Al-12.6Si with 1 wt% Mn is found to give more uniform stress and deformation distribution, therefore the simulated results have a great concurrence with the experimented results.