Methods
This study employed cyclic torsion to process Al$_{0.1}$CoCrFeNi multi-principal element alloy samples, and their microstructures were characterized using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The two-beam diffraction imaging technique in TEM was used to analyze the dislocation characteristics under different cumulative plastic strains.
Extensive proliferation of multi-slip dislocations: At larger cumulative plastic strains, the formation of dislocation locks induced the extensive proliferation of multi-slip dislocations, which is distinct from the single-slip dislocation behavior observed in conventional low stacking fault energy metals. Formation of two-dimensional and three-dimensional dislocation structures: With increasing cumulative plastic strain, multiple dislocations gradually organized into two-dimensional micrometer-scale dislocation wall segments and eventually formed three-dimensional equiaxed low-angle dislocation cells. Gradient distribution of dislocation structures: Cyclic torsion resulted in a sample-level gradient distribution of dislocation structures, characterized by a gradual decrease in dislocation cell size from the sample surface to the core.
Fig. 1. Coplanar-slip full dislocations dominated plastic deformation inside the cells at γcu = 14.6 under [10–1] axis (a). (b-f) Five double-beam diffraction images under g = 020 (b), 111 (c), -11-1 (d), 220 (e) and 13–1 (f) identified the Burgers vectors and slip systems of dislocations.
Authors
The first author of this work is L.X. Zhang from the Institute of Metal Research, Chinese Academy of Sciences. Prof. Qing-Song Pan and Prof. Lei Lu from the Institute of Metal Research, Chinese Academy of Sciences are the corresponding authors of this paper.
