Abstract
High-strength aluminium (Al) alloys are prone to hot cracking defects during additive manufacturing (AM) due to extensive columnar grain growth and a large solidification range. Recent studies have demonstrated the effectiveness of inoculation treatment in addressing the non-printability of high-strength Al alloys by promoting the formation of equiaxed grains. Since then, significant progress has been made in controlling microstructure and improving the mechanical properties of these alloys. This state-of-the-art review presents the emerging research on inoculated high-strength Al alloys fabricated through two major AM technologies: powder bed fusion (PBF) and directed energy deposition (DED). The efficiency of different inoculants and alloying elements in grain refinement are discussed based on the existing theories. Novel processing strategies for controlling the microstructures of these inoculated high-strength Al alloys are also examined. This review underscores that grain refinement in inoculated high-strength Al alloys produced via AM depends on multiple factors, including the selection of inoculants, inoculation techniques, solute elements, and processing strategies. While recent studies mainly focus on modifying alloy compositions, this review emphasizes the critical role of solidification process control in regulating the grain structure. Numerical simulations specifically developed for predicting the grain structure of these alloys, which can aid in the process optimization, are also reviewed. The subsequent discussion covers the effect of inoculation treatment on mechanical properties. The article concludes by outlining the major findings and presenting future outlooks. This review aims to provide comprehensive insights into microstructural control and to advance the understanding of the process-structure-properties relationship in inoculated high-strength Al alloys manufactured via AM, thereby facilitating future developments in this innovative research area.