D0₂₂ 相强化型 Ni₂CoCrFeNb_0.15 高熵合金的变形机理

In the present study, the texture evolution, deformation substructure characteristics, dislocation-precipitate interaction and fracture behavior of the D0₂₂-hardened Ni₂CoCrFeNb_0.15 high entropy alloy during uniaxial tensile deformation were evaluated by transmission electron microscope (TEM), electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) based on scanning electron microscope. The results show that the plane slip of the dislocation dominates the uniaxial tensile deformation of the alloy, and the D0₂₂ superlattice phases are the main factor to promote the plane slip of the dislocation. The plane slip mode of the dislocation leads to the plane slip band as the characteristic deformation substructure. When the strain level increases, the plane slip band density increases and the mean distance decreases. In the deformation process, the {001} texture is formed first, then the {111} texture is enhanced, and finally the typical {001} and {111} tensile textures are obtained. When the stress reaches maximum value during uniaxial tensile deformation, the cracks originate the grain boundary and further propagate to form the main fracture crack, resulting in plastic instability.