A novel approach for tailoring aluminum alloys for additive manufacturing

Abstract

Wrought aluminum alloys are known for their excellent mechanical properties, but they also exhibit high hot-cracking susceptibility, limiting their use in additive manufacturing (AM). While indices such as freezing range, hot-cracking susceptibility index, and critical temperature range, based on the classic Scheil-Gulliver model, have been used to adapt wrought aluminum alloys for AM, they are unable to sufficiently capture the effects of high stresses induced during processing, which contribute to crack formation. In this study, we introduce a novel approach that combines thermodynamic calculations with laser remelting experiments to optimize aluminum alloys for AM. We applied this methodology to modify the AA2017 alloy, starting with thermodynamic calculations that screened hundreds of compositions to optimize solidification behavior using the Scheil-Gulliver model. Nine compositions were selected for further investigation through laser remelting experiments, simulating the stresses experienced during processing. The most promising alloy was then produced as powder via gas atomization and fabricated using Laser Powder Bed Fusion. This new alloy demonstrated a significantly narrower solidification range, a low hot-cracking susceptibility index, and the formation of α_Al + Al₃CeCu eutectic regions, along with a higher liquid fraction during the final stages of solidification. Unlike the original AA2017, no cracks formed during the processing optimization. This approach led to the development of a new alloy with enhanced mechanical properties, showing substantial improvements in both tensile strength and ductility compared to existing AM aluminum alloys.