Design approaches for printability-performance synergy in Al alloys for laser-powder bed additive manufacturing

Abstract

The unprecedented increase in component design space has led to significant focus on fusion-based additive manufacturing (AM) technologies. The new design possibilities integrate features and functionalities that are not supported by conventional manufacturing, and simultaneously achieve unitization of components. However, fusion-based AM suffers from a lack of diverse alloys, as conventional high-strength Al alloys are prone to hot cracking and other defect formation during printing. New alloy design approaches are being pursued to overcome these limitations. Current strategies for design of printable Al alloys for laser-powder bed fusion (L-PBF) are primarily experimental and revolve around grain refinement and eutectic solidification (ES). Each of these strategies targets hot cracking at only a specific stage of solidification. Consequently, the processing window of the alloy shrinks and fine-tuning of the alloy microstructure becomes difficult, thus prohibiting the activation of multiple deformation mechanisms. On the other hand, strategies that integrate microstructural refinement (MR) and ES attack the problem during multiple stages of solidification. Such MR+ES integrated alloy design strategies allow widening of alloy-processing-window (printability) and activation of multiple deformation mechanisms such as back-stress strengthening and work-hardening, thus producing alloys with excellent synergy of printability and performance.

Keywords

• Alloy design
• Additive manufacturing
• Al alloys
• Laser-powder bed fusion
• Solidification
• Microstructure