Hydrogen-induced compatibility constraints across grain boundaries drive intergranular failure of Ni
Hydrogen-induced compatibility constraints across grain boundaries drive intergranular failure of Ni
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DOI：
10.1016/j.msea.2019.05.036
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发表时间：
2019-07-08
期刊：
影响因子：
6.4
通讯作者：
Robertson, I. M.
中科院分区：
文献类型：
--
作者：
Bertsch, K. M.;Wang, S.;Robertson, I. M.
多尺度实验方法被用来确定的基本机制，负责氢诱导过渡的破坏模式从韧性穿晶到晶间的多晶镍在单轴加载。氢加速了变形显微组织的演变，产生更小的位错胞和微带，并导致显着不同的取向偏差，以发展在相邻的晶粒，同时诱导较少的织构演变，较少的晶粒旋转，较少的伸长率平行于拉伸轴的晶粒，和更大的表面外变形的晶粒。这些观察结果解释的氢增强塑性机制，这导致在一个重新分配的氢，稳定变形的微观结构，并增加了氢覆盖在晶界上。微观结构的稳定化表现为晶粒协同适应不断变化的变形结构的能力降低，这在晶界上引入了额外的相容性约束。这种跨晶界的相容性约束、通过氢将微观结构锁定在特定配置中以及晶界的氢弱化的组合驱动氢诱导的晶间失效。
A multi-scale experimental approach was used to determine the fundamental mechanisms responsible for the hydrogen-induced transition in failure mode from ductile transgranular to intergranular in polycrystalline Ni during uniaxial loading. Hydrogen accelerated the evolution of the deformation microstructure, producing smaller dislocation cells and microbands, and causing significantly different orientation deviations to develop in neighboring grains, while inducing less evolution of texture, less grain rotations, less elongation of the grains parallel to the tensile axis, and greater out-of-surface distortion of the grains. These observations are explained in terms of the hydrogen-enhanced plasticity mechanism, which results in a redistribution of hydrogen that stabilizes the deformed microstructure and increases the hydrogen coverage on the grain boundaries. The stabilization of the microstructure manifests as a reduced ability of grains to cooperatively accommodate evolving deformation structures, which introduces an additional compatibility constraint across grain boundaries. The combination of this compatibility constraint across grain boundaries, the locking of the microstructure in a specific configuration by hydrogen, and the hydrogen-weakening of the grain boundaries drives the hydrogen-induced intergranular failure.