Recent progress in wire-arc and wire-laser directed energy deposition (DED) of titanium and aluminium alloys

Wire-based directed energy deposition (DED) techniques have emerged offering the ability to manufacture large-scale metal components in the additive manufacturing landscape. Wire-based DED processes offer high deposition rates, material use efficiency, and suitability for a wide range of metals and alloys. On the other hand, these processes are limited in terms of dimensional accuracy of deposition, surface quality, and ability to produce highly complex geometry. Therefore, this review aims to provide a comprehensive analysis of recent advancements in wire-arc and wire-laser DED processes-with a specific focus on widely used titanium and aluminium alloys for aerospace applications with low buy-to-fly (BTF) ratio. It provides an overall understanding of wire-based DED processes and guides the reader with the choice to make appropriate process selection. Moreover, the study provides a discussion on the process intricacies, encompassing an overview of wire-based DED equipment and process capabilities, as well as an examination of critical process parameters. A detailed comparison is provided between wire-arc and wire-laser DED processes, covering essential aspects like path planning, deposition strategy, melt pool behaviour, obtained microstructures and mechanical properties, part quality, and defect mitigation. Additionally, post-processing techniques tailored for end-use applications are reviewed providing insights for achieving optimal results. The discussion extends to process monitoring and control, emphasising in situ techniques and process modelling for enhanced precision and efficiency. Finally, recommendations and highlights on potential areas for innovation and development as the future work are provided.