Toward Understanding the Mechanism behind Microstructure Development of Aluminum Alloy Powders Additively Manufactured by Selective Laser Melting

The present article describes a possible mechanism behind the microstructure development in aluminum (Al) alloy (AlSi10Mg: Al–10wt%Si–0.3wt%Mg) parts additively manufactured by selective laser melting (SLM) combined with powder bed system (one of the most conventional additive manufacturing processes for metals). It introduces the thermodynamic calculation applied to the studied alloy to understand the microstructure development during the SLM process and then elaborates microstructural features of SLM-fabricated Al alloy parts characterized by electron microscopy and electron back-scattered diffraction analyses. The aforementioned results are utilized to present the formation process of microstructure through the rapid solidification during the SLM process. An attempt was made to quantify the cooling rate and molten pool dimensions using the preliminary two-dimensional finite element model. The analyzed thermal gradient and cooling rates are presented as well.