Wei, S., Huang, S., Ng, S. J., Zhang, L., Zeng, Y., Wang, P., & Ramamurty, U. (2025). Suppressing cold cracking in laser powder bed fused Al-Fe-V-Si alloy using top-hat laser profile. Materials Science and Engineering: A, 924, 147858. https://doi.org/10.1016/j.msea.2025.147858
Abstract:
Dispersion-strengthened Al-Fe-V-Si alloy that has high temperature applicability was additively manufactured using the laser powder bed fusion (LPBF) technique with both Gaussian and top-hat laser profiles. The fabricated samples were investigated through multiscale microstructural characterization, hardness mapping, and bulk mechanical testing. The Gaussian laser induced severe cold cracking along the melt pool boundaries, even with extensive parameter optimization and substrate pre-heating up to 200 °C. In contrast, the top-hat laser effectively suppressed cold cracking, producing nearly fully dense samples with only 110 °C preheating. Transmission electron microscopy analysis identified fine Al₁₂(Fe,V)₃Si and coarse h-AlFeSi precipitates in the built part, which were not predicted by the equilibrium and Scheil-Gulliver thermodynamic models, indicating non-equilibrium conditions and complexity in their formation. The brittle coarse precipitates along the melt pool boundaries were identified to be the key cause of cold cracking in the Gaussian laser samples, creating a hardness mismatch between the melt pool boundary and the interior. The top-hat laser created a large heat-affected zone that spanned more than one layer thickness, effectively achieving in-situ "substrate" preheating, which contributed to crack mitigation.
License type:
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Funding Info:
This research / project is supported by the Agency for Science, Technology and Research - Structural Metal Alloys Programme
Grant Reference no. : A18B1b0061
This research / project is supported by the Agency for Science, Technology and Research - Development of High-Performance Electric Traction Module
Grant Reference no. : M22K4a0044