Article Dans Une Revue Scripta Materialia Année : 2026

Dislocation evolution and redistribution during stress relaxation in single crystal AD730TM after prior plastic strain at 700 °C

Résumé

Understanding dislocation evolution during viscoplastic deformation is essential to accurately predict high-temperature superalloy behavior. While creep and monotonic deformation are well studied, the evolution of the dislocation substructures during stress relaxation, particularly following prior plastic straining, remains unclear. This study investigates a single crystal γ/γ' AD730TM superalloy deformed at 700 °C, focusing on dislocation evolution and redistribution. Transmission electron microscopy reveals that stacking faults formed during plastic straining progressively disappear during relaxation, suggesting thermally activated mechanisms such as dislocation re-association and recovery. After re-association, perfect dislocations spread into the matrix, forming a homogeneous dislocation network. These microstructural evolutions are believed to underlie the macroscopic stress relaxation behavior, which exhibits two regimes in the Norton diagram: an initial high-stress exponent regime linked to rapid dislocation rearrangement, followed by a low-stress exponent regime associated with broader dislocation activity.

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Dates et versions

hal-05407125 , version 1 (09-12-2025)

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Fabio Machado Alves da Fonseca, Patrick Villechaise, Malik Durand, Arnaud Longuet, Florent Coudon, et al.. Dislocation evolution and redistribution during stress relaxation in single crystal AD730TM after prior plastic strain at 700 °C. Scripta Materialia, 2026, 271, pp.117009. ⟨10.1016/j.scriptamat.2025.117009⟩. ⟨hal-05407125⟩
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