Cold gas dynamic spraying is a solid-state deposition technology that enables the fabrication of dense metallic coatings. Applied to the Al6061 alloy, this technique shows strong potential for the local reinforcement of extruded profiles in the road transportation industry. However, as sprayed deposits are characterized by a severely deformed microstructure, rich in dislocations and residual stresses, which limits their ductility and service reliability.
This work aims to characterize the influence of post-deposition heat treatments on the microstructural and mechanical evolution of these coatings. The primary objective is to identify the thermally activated recovery and recrystallization mechanisms, as well as their respective impacts on dislocation density, grain size, and overall mechanical performance.
The methodology is based on experiments including heat treatments (200 °C to 300 °C) and a full T6 aging cycle. Characterization techniques include optical and electron microscopy, EBSD analyses (grain size, KAM, LAGB/HAGB fraction), and X-ray diffraction (XRD), using the full width at half maximum (FWHM) of the (222) peak as an indicator of dislocation density. The evolution of the coatings mechanical properties was monitored via hardness and micro-tensile tests, revealing transitions between work hardening, recovery and precipitation.
The analyses demonstrate that heat treatments promote a progressive relaxation of the initially work-hardened microstructure. Parameter optimization allows assessing the impact of recovery conditions on mechanical strength, in comparison with the T6 cycle, which ensures full structural homogenization of the coating. Finally, the study reveals a marked spatial heterogeneity within the deposit, as microstructural evolution is influenced by the local deformation history of the particles. Overall, these observations provide key guidelines for adapting heat treatments to ensure the performance and durability of Al6061 components used in the road transportation industry.
| Date | 16 Aug 2026 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Philippe Bocher (Supervisor) & Lucas Hof (Supervisor) |
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Legrand, L. (Author),
Bocher (Supervisor) &
Hof (Supervisor),
16 Aug 2026Student thesis: Master's thesis › Master in Engineering: Automated Manufacturing Engineering