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采用考虑非均匀微观结构的非局部位错密度晶体塑性有限元模型,研究金属晶体薄膜材料微弯曲塑性变形的特点。该模型采用统计存储位错密度和几何必需位错密度作为其内部状态变量,通过几何必须位错密度的演化来预测单晶体金属薄膜材料微弯曲中的应变梯度效应。采用不同晶粒大小的CuZn37α-黄铜多晶体薄膜进行微弯曲实验,并测量试样微弯曲变形后的微硬度分布图。将模拟得到的位错密度分布与实验测得的微硬度分布进行对比,发现粗晶试样和细晶试样微硬度分布的不同主要是由统计存储位错密度和几何必须位错密度引起的。基于微观物理机理,研究微弯曲变形的特点和位错密度的演化。
The non-local dislocation density plasticity finite element model considering non-uniform microstructure is used to study the characteristics of micro-plastic deformation of metal crystal thin film. In this model, the statistical storage dislocation density and the geometrically necessary dislocation density are taken as the internal state variables. The evolution of the geometric dislocation density is used to predict the strain gradient effect in the micro-bending of the single crystal metal thin film material. Micro-bending experiments were carried out on CuZn37α-brass polycrystalline films with different grain sizes, and the microhardness distribution after the micro-bending deformation was measured. Comparing the simulated dislocation density distribution with the experimentally measured microhardness distribution, it is found that the difference of microhardness distribution between the coarse-grained sample and the fine-grained sample is mainly caused by the statistical storage dislocation density and geometric dislocation density . Based on the micro-physical mechanism, the characteristics of micro-bending deformation and the evolution of dislocation density are studied.