Mapping challenges and pathways forward in multi-metal additive manufacturing: A scoping review

The advancement of metal additive manufacturing has enabled the growth of multi-metal additive manufacturing (MMAM) in the recent decade. MMAM has since been extensively studied due to its vast benefits for real-life application such as tailored material properties, gradient multifunctionality with embedded structures in a complex geometry. These attractive features have potential for use in industrial component repairs, biomedical, nuclear reactor and aerospace industries. A growing interest has been recorded with the rise of publications and media exposure in the MMAM field. This scoping review aims to map the current MMAM research landscape across the recent decade (2016 – 2026) with a specific focus on the challenges and their root causes. This work established a framework for MMAM challenges mitigation strategies by deliberating on the root causes of each challenge and their highlighted solutions. This review has highlighted the three main challenges in MMAM including process control complexity, material incompatibility and interface performance. Mitigation strategies for each challenge have also been highlighted to include integration of artificial intelligence and machine learning for process control optimization, predictive modelling and material selection design to ensure successful bonding and interface engineering route to mitigate defects in interface of MMAM. Outlook of MMAM underlines the need for these mitigation strategies to be implemented through collaboration of academia and industrial partnership. Future works are recommended to focus more on the sustainability, standardization and qualification of MMAM parts for industrial implementation.