Enhancing microstructure and mechanical properties of LMD-fabricated Al-Mg-Sc-Zr alloy via post-process rolling: A comprehensive study of porosity, dislocation, and mechanical properties

In this study, an Al-Mg-Sc-Zr alloy fabricated by laser metal deposition (LMD) was subjected to post-process hot rolling at varying deformation levels (50%, 60%, and 70%) to investigate their effects on microstructure and mechanical properties. The as-deposited alloy exhibited significant porosity and microstructural heterogeneity, attributed to the high reflectivity and thermal conductivity of aluminum during laser processing. Quantitative metallographic analysis revealed that rolling dramatically reduced porosity, achieving a maximum reduction of ~98% at 70% strain. Electron backscatter diffraction (EBSD) and geometrically necessary dislocation (GND) analyses showed a progressive increase in dislocation density and low-angle grain boundaries with increasing strain, indicating enhanced plastic deformation-induced substructure refinement. The crystallographic texture evolved from random orientations to well-developed face-centered cubic (FCC) rolling textures dominated by Copper ({112}⟨111⟩), Brass ({011}⟨211⟩), and Goss ({011}⟨100⟩) components. Backscattered electron (BSE) imaging and energy-dispersive spectroscopy (EDS) confirmed that Sc- and Zr-rich Al₃(Sc,Zr) dispersoids remained morphologically stable throughout deformation, contributing to grain stabilization and strengthening. Mechanical testing demonstrated concurrent improvements in strength and ductility at moderate deformation levels (50–60%), whereas excessive rolling (70%) led to reduced elongation due to strain hardening saturation. These findings underscore the effectiveness of thermomechanical post-processing in optimizing LMD-fabricated aluminum alloys for structural applications.