Fundamental Study on the Development of Pure Magnesium Parts by Additive Manufacturing: An Experimental and Computational Analysis

다국어 초록 (Multilingual Abstract)

The low density and high biocompatibility of Mg-based materials make them suitable for lightweight structural and biomedicalapplications. In this study, we explored the use of selective laser melting (SLM)–an additive manufacturing processwherein metal powders are consolidated in a layer-by-layer manner, allowing the fabrication of complex components. SLMtypically involves complex physicochemical phenomena and results in laser-processing defects, which makes it difficult topredict the densification mechanisms of the melt pool. Therefore, a full-scale model was developed to investigate the thermalbehavior of the melt pool (e.g., temperature gradient distribution, melt pool dimensions, and cooling rate) and the resultantdensification activity under various laser energy density (η) values. In parallel, experimental investigations of the densificationbehavior and microstructural evolution were undertaken with the same SLM processing parameters. The challengesassociated with the SLM processability of Mg were comprehensively addressed. Both the peak temperature gradients withinthe molten pool and molten pool dimensions increased with increasing η, and an opposite trend was observed for the coolingrate. A low η (i.e., high scanning speed) results in a low operating temperature and short liquid lifetime, which in turn leadto poor wettability and many pore-chain and balling defects. However, high η values generated melt pool instability, whichresulted in extensive evaporation, cracks, and porosity. The SLM-processed samples had fine twin-like microstructures asa result of rapid solidification. The experimental and simulation results agreed well, validating the thermal behavior of themolten pool and underlying physical mechanism.