Abstract:The deformation characteristics and activation mechanisms of kink bands in refractory multi-principal element alloys with local chemical fluctuations (LCFs) were systematically studied. These alloys were fabricated using laser-directed energy deposition technology and characterized by room-temperature compression testing, electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and high-angle annular dark-field (HAADF) imaging. The results reveal that kinking is a gradual rotational diffusion process, during which the misorientation difference between the kink and the matrix varies. A low Schmid factor is a prerequisite for kink excitation. The slip system closest to the loading axis is passively activated by the applied external force, leading to the accumulation of geometrically necessary dislocations (GNDs) required for lattice rotation. The widespread LCFs within the matrix reduce the migration rate of edge dislocations, promoting GND accumulation and enhancing the propensity for kink band formation. During deformation, the occurrence of kinking enables continuous lattice rotation to accommodate the exceptionally high strain in the vicinity, when the stress concentration in the primary kink cannot be fully released, double kinks are activated to reduce strain energy.

Key words: refractory multi-principal element alloys; plastic deformation; kink band; Schmid factor; local chemical fluctuation