Effect of Long-Term Aging on the Microstructure and Mechanical Properties of LPBF-Fabricated F357 (Al-7Si-Mg) Alloy

Monday, September 28, 2026: 10:00 AM
302B (Québec City Convention Centre)
Ms. Gargee Dash , McGill University, Montreal, QC, Canada
Prof. Mathieu Brochu , REGAL Aluminum Research Center, Department of Mining & Materials Engineering, McGill University, Montreal, QC, Canada
The long-term reliability of LPBF-manufactured F357(AlSi7Mg) alloy parts depends on their microstructural and mechanical stability under extended thermal exposure. This work investigates the microstructural evolution and mechanical properties of LPBF-fabricated F357 soaked at 149 °C (300oF) for durations up to 1000 hours. SEM analysis shows time-dependent coarsening of Si particles, modeled using the Lifshitz–Slyozov–Wagner (LSW) theory. The activation energy for Ostwald ripening is calculated as ~68 kJ/mol, suggesting grain boundary diffusion as the dominant mechanism. Vickers hardness and tensile tests reveal a peak in strength at intermediate exposure times, followed by softening with further aging. Fractography supports a correlation between coarsening and loss in ductility. These findings contribute to understanding the thermal stability and aging kinetics of LPBF AlSi7Mg alloys, with implications for their performance in extended service environments.

Keywords: Al-Si-Mg alloy; long-term aging; LPBF; Ostwald ripening; coarsening kinetics; thermal exposure.

See more of: Laser Powder Bed Fusion: Surface Integrity, Process Control, and Alloy Performance I
See more of: Additive Manufacturing, organized by the Additive Manufacturing Programming Committee