Microstructural and corrosion studies on hybrid additively manufactured aluminium silicon magnesium alloys

Samson Dare  Oguntuyi

Hybrid Additive Manufacturing (HAM), which incorporates additive and subtractive manufacturing processes, has developed as a transformative route for fabrication intricate high-performance parts with enhanced surface quality and precision. Al-Si-Mg alloys, widely applied in additive manufacturing because of their excellent strength-to-weight ratio, wear resistance, and corrosion properties, present significant challenges in HAM, specifically at the built-substrate interface. Hence, in defining the general bonding quality, mechanical integrity, and tribological and corrosion behaviour of the final parts, the interfacial region is important to examine. The interfacial phenomena in HAM present major challenges, including microstructural heterogeneity, residual stresses, bonding integrity issues, and differences in corrosion resistance. These concerns are primarily influenced by solidification dynamics, steep thermal gradients, and elemental diffusion at the junction between the conventionally cast substrate and the additively deposited material. These typical interactions can lead to defects, weak bonding, microcracks, and porosity, all of which unfavorably impact the electrochemical stability and corrosion performance of HAM-fabricated components, particularly under aggressive service conditions or elevated mechanical stress. While hybrid and additive manufacturing techniques have advanced significantly, a full understanding of how microstructural evolution and bonding at the built–substrate interface influence corrosion behavior is still growing. This study explores the corrosion resistance of hybrid Al–Si–Mg structures prepared through SLM-Cast combinations, specifically: Sample 1 (Al 10 on Al 5083), Sample 2 (Al 10 on Al 6061), Sample 3 (Al 10 on Al 6082), Sample 4 (Al 7 on Al 5083), Sample 5 (Al 7 on Al 6061), and Sample 6 (Al 7 on Al 6082). Using detailed microstructural analysis and electrochemical techniques, the work examines how different electrolytes, pH conditions, elemental composition, and fabrication pathways influence the stability and performance of the built–substrate interfaces as well as the individual sections of the hybrid configuration. By doing so, it aims to provide insight into the corrosion mechanisms governing hybrid aluminium systems and to guide the development of more durable components suited for harsh service environments. The hybrid Al–Si–Mg structures exhibited varying overall corrosion resistance, governed by the contrasting processing routes of the additively manufactured and cast substrate regions, as well as their compositional differences. Examination of the galvanic corrosion behaviour of...

Microstructural and corrosion studies on hybrid additively manufactured aluminium silicon magnesium alloys

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