Enhanced mechanical performance via laser induced nanostructure formation in an additively manufactured lightweight aluminum alloy

To date, the primary focus of metal additive manufacturing (AM) research has been the development of strategies for fabricating complex architectures, reducing internal stress and optimizing microstructure. Traditional Al alloys have presented further challenges in this effort due to solidification cracking and complex laser coupling dynamics. To overcome these limitations, identification of novel alloys that exploit the rapid solidification conditions inherent in laser-based AM is required. In this work, laser-induced melting of an Al-8Ce-10Mg alloy is revealed to generate a nanoscale microstructure which results in improved hardness, tensile strength, and mitigated solidification cracking (e.g., hot tearing) in single laser tracks in as-cast material and laser powder bed fusion (LPBF)-fabricated components. In situ X-ray imaging shows the nanostructure arises from laser-induced melting of intermetallic particles embedded into the alloy during casting and then rapid resolidification of the molten material in similar to 400 mu s. The formed Ce-rich nanostructures are highly resistant to thermal coarsening at 300 degrees C, as confirmed by microscopy and retention of tensile properties. These results pave the way for development of AM-specific Al alloys that possess the ability to form mechanically favorable nanostructures in fabricated components due to the rapid cooling inherent in LPBF. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The primary focus of metal additive manufacturing research has been on developing strategies for fabricating complex structures and optimizing microstructure. New alloys that exploit rapid solidification conditions are needed to overcome challenges in traditional aluminum alloys. Laser-induced melting of Al-8Ce-10Mg alloy has been shown to generate nanoscale microstructures, improving hardness and tensile strength while mitigating solidification cracking.