Cryogenic deformation-induced dislocation behavior and substructural evolution in 6061 aluminum alloy

ZH Zhao and YP Yi and SQ Huang and HL He and JL Hu, JOURNAL OF ALLOYS AND COMPOUNDS, 1041, 183781 (2025).

DOI: 10.1016/j.jallcom.2025.183781

This study systematically investigates the cryogenic deformation behavior of 6061 aluminum alloy using a multiscale approach integrating EBSD, TEM, nanoindentation, and molecular dynamics (MD) simulations. The results reveal that deformation at -196 degrees C suppresses dynamic recovery and dislocation entanglement, promoting dislocation slip along 111 planes and dislocation dissociation. This leads to the formation of dense, lowentanglement dislocation networks. Concurrently, a progressive increase in low-angle grain boundaries (LAGBs) and kernel average misorientation (KAM) indicates continuous lattice rotation and substructure evolution, ultimately facilitating geometry-driven dynamic recrystallization (GDRX) and the formation of lamellarlike refined grains. In contrast, room-temperature deformation is dominated by recovery, with limited lattice rotation and no significant grain refinement. Nanoindentation tests confirm enhanced hardness and greater plastic work absorption after cryogenic deformation. Atomistic simulations further demonstrate longer, straighter dislocation lines and a reduced proportion of 1/6 < 110 > stair-rod dislocations at -196 degrees C, consistent with smoother, planar slip. Together, these findings establish a dislocation-to-substructure-to-microstructure hierarchy, elucidating the fundamental mechanisms responsible for cryogenic plasticity enhancement. These findings offer theoretical guidance for the design of cryogenic forming strategies aimed at enhancing precision aluminum components.

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