Casting assisted design of a high-performance Sc-free Al-Mg-Si-Zr alloy for laser powder bed fusion

In this study, we present the successful design of a tailored Al-Mg-Si-Zr alloy for laser powder bed fusion (PBF-LB/M), combining high strength and adequate ductility with excellent processability. High-strength commercial aluminum alloys, such as 2024 or 7075, exhibit poor printability and are prone to hot cracking, which makes them challenging to process via PBF‑LB/M. This leads to a high demand for customized Al-based alloys. Moreover, from a sustainability perspective, the use of rare-earth elements, such as scandium, should be avoided. This work demonstrates an approach for designing alloys for PBF-LB/M, based on centrifugal casting. Without the need for pre-alloyed powder, various compositions were produced by applying this rapid cooling technique to roughly estimate their thermophysical properties, microstructure, and mechanical properties. Key characteristics such as freezing range, 0.2% compressive yield strength, ultimate strength and corresponding strain were determined by differential scanning calorimetry and compression tests. Based on the initial results, the most promising composition predicted to balance high-performance and superb printability, was atomized into powder and successfully employed in PBF-LB/M. Relative densities of more than 99.5% without crack formation were achieved for several laser powers and scanning velocities, along with promising mechanical properties, including a compressive yield strength of almost 400 MPa in the as-built state.