Study of the influence of silicon phase morphology on the microstructural stress distribution in Al-Si alloys using object oriented finite element modeling

Abstract

Near-eutectic Al-Si alloys were produced by conventional casting and spray forming resulting in microstructural differences due to process dependent cooling rates. The as-sprayed alloy exhibited fine equiaxed Si particles uniformly distributed throughout the matrix in contrast to the as-cast alloy, which exhibited acicular morphology with relatively large needle-like Si particles. The effect of Si morphology on the microstructural stress distribution of the as-cast and as-sprayed alloys was estimated by simulating uni-axial tensile loads on microstructures using Object Oriented Finite Element code (OOF2). Microstructures of the as-sprayed alloy experienced relatively low and uniform stress distribution, while the microstructural stress distribution in the as-cast alloy was significantly influenced by the orientation of the needle shaped silicon particles. Near-eutectic Al-Si alloy is processed through casting and spray forming. Microstructure of as-cast alloy shows acicular needle-like morphology of silicon particles while spray formed alloy shows uniform distribution of fine and equiaxed silicon particles. Microstructure-based finite element analysis shows strong orientation dependence of Si on the stress distribution in as-cast alloys in contrast to as-sprayed alloys. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.