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Atomic Force Microscopy Study of Discrete Dislocation Pile-ups at Grain Boundaries in Bi-Crystalline Micro-Pillars
Crystals ( IF 2.7 ) Pub Date : 2020-05-20 , DOI: 10.3390/cryst10050411
Xiaolei Chen , Thiebaud Richeton , Christian Motz , Stéphane Berbenni

Compression tests at low strains were performed to theoretically analyze the effects of anisotropic elasticity, misorientation, grain boundary (GB) stiffness, interfacial dislocations, free surfaces, and critical force on dislocation pile-ups in micro-sized Face-Centered Cubic (FCC) Nickel (Ni) and α -Brass bi-crystals. The spatial variations of slip heights due to localized slip bands terminating at GB were measured by Atomic Force Microscopy (AFM) to determine the Burgers vector distributions in the dislocation pile-ups. These distributions were then simulated by discrete pile-up micromechanical calculations in anisotropic bi-crystals consistent with the experimentally measured material parameters. The computations were based on the image decomposition method considering the effects of interphase GB and free surfaces in multilayered materials. For Ni and α -Brass, it was found that the best predicted step height spatial profiles were obtained considering anisotropic elasticity, free surface effects, a homogeneous external stress and a certain critical force in the material to equilibrate the dislocation pile-ups.

中文翻译:

双晶体微柱晶粒边界离散位错堆积的原子力显微镜研究。

进行了低应变压缩试验,以理论分析各向异性弹性,取向错误,晶界(GB)刚度,界面位错,自由表面和临界力对微型面心立方(FCC)中位错堆积的影响镍(Ni)和 α -黄铜双晶体。通过原子力显微镜(AFM)测量了由于局部滑带终止于GB而引起的滑移高度的空间变化,以确定位错堆积中的Burgers矢量分布。然后通过与实验测量的材料参数一致的各向异性双晶体中的离散堆积微机械计算来模拟这些分布。该计算基于图像分解方法,其中考虑了多层材料中相间GB和自由表面的影响。对于镍和 α -黄铜,发现考虑到各向异性弹性,自由表面效应,均匀的外应力和材料中的一定临界力来平衡位错堆积,获得了最佳的预测台阶高度空间分布。
更新日期:2020-05-20
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