Development of a new high-strength diffusion-assisted healable Al-Mg-Zr alloy produced by Powder Bed Fusion - Laser Beam/Metals

Additive manufacturing enables complex lightweight aluminium components but often generates microvoids or microcracks degrading the mechanical properties. Introducing healing ability into high-strength Al alloys could mitigate these defects and improve structural integrity. A new high-strength and healable Al-Mg-Zr alloy, Almazium®, was developed and processed by Powder Bed Fusion - Laser Beam/Metals (PBF-LB/M). High Mg content and Zr-induced grain refinement produce a fine bimodal microstructure and a yield strength of 317 MPa in the as-built condition. Synchrotron X-ray nano-holo-tomography revealed that a Healing Heat Treatment (HHT) at 540 ∘C for 30 min fully closed 65 % of submicrometric voids, with complete healing up to 3.7 µm. At 400 ∘C, 90 % of submicrometric voids were fully healed, with a maximum healed size of 1.5 µm. Scanning Transmission Electron Microscopy and Atom Probe Tomography revealed a high Mg content in solid solution, supporting a Mg diffusion-based healing mechanism. The healing behaviour was maintained after a second thermal cycle, confirming the alloy’s re-healability. Under combined heat and pressure, the healing efficiency increased drastically, allowing full closure of voids up to at least 100 µm. These findings demonstrate that Almazium® combines high mechanical strength with intrinsic, replicable healing ability.