通过数字图像相关方法获取全场应变信息, 从应变非均匀性的角度研究Ni单晶体的加工硬化行为. 首先提出一种适用于描述单晶体变形的数字图像相关方法, 用于准确获取应变场. 拉伸实验结果表明, Ni单晶体的塑性应变具有显著的局部化特征, 这与滑移带的形成、发展密切相关. 根据应变场的演化特征, 3种变形机制可被确定, 且发现它们与材料的3个加工硬化阶段具有一一对应关系. 在位错理论框架下, 两者之间的内在联系得到了合理的解释, 并通过对材料微观结构演化的实验观测得到了很好的验证.

Metals exhibit inhomogeneous deformation features under plastic strain, leading to the appearance and evolution of the deformation bands. The quantitative characterization of this effect is significant for an in-depth understanding of the plastic deformation and strengthening mechanisms of metals. In this work, the full-field strain information are obtained using digital image correlation method, and the work hardening behaviour in Ni single crystals is investigated from the angle of strain heterogeneity. First, a digital image correlation method, adapted for characterizing single crystal deformation, is proposed for the precise evaluation of strain field. The tensile test results show that the plastic strain in Ni single crystal manifests a distinct localization characteristic, which is closely linked to the slip band formation and development process. Based on the characteristics of the strain field evolution, 3 deformation regimes can be determined, which demonstrate a one-to-one correspondence to the 3 work hardening stages of the material. Some reasonable interpretations of their correlation are proposed within the framework of dislocation theories, which are verified through the experimental observations on the microstructure evolution of the material.