Additive manufacturing of Al-4043 by molten metal deposition: coupled thermal modeling and microstructural characterization

Molten Metal Deposition (MMD) is an emerging additive manufacturing process for aluminum alloys that operates without forming a localized melt pool, instead depositing a continuous stream of molten metal, thereby reducing porosity and thermal distortion. In this study, a coupled numerical–experimental framework is developed to investigate the influence of process parameters on thermal behavior, porosity, and mechanical properties of AA 4043 structures. A conduction-based finite-element thermal model with element-wise activation was implemented to mimic layer-wise deposition and validated against in-situ thermocouple measurements at multiple build heights using root-mean-square error (RMSE) as a quantitative metric. Within the investigated parameter window, the approach identifies parameter sets yielding measured cross-sectional porosity below 0.1%, ultimate tensile strength up to 132 MPa, and elongation up to 21–23%. SEM–EDS mapping revealed directional eutectic Si-rich film evolution along columnar α-Al grains, closely linked to local cooling rates. Overall, the results demonstrate MMD’s viability for producing Al-4043 wall structures with low porosity and favorable strength–ductility combinations within the studied conditions, while providing a model-driven framework for parameter tuning in melt-pool-free deposition.