Hydrogen embrittlement in nickel, visited by first principles modeling, cohesive zone simulation and nanomechanical testing
Hydrogen embrittlement in nickel, visited by first principles modeling, cohesive zone simulation and nanomechanical testing
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DOI：
10.1016/j.ijhydene.2015.06.069
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发表时间：
2015-12-21
影响因子：
7.2
通讯作者：
Olden, V.
中科院分区：
文献类型：
--
作者：
Alvaro, A.;Jensen, I. Thue;Olden, V.
氢（H）可对材料性能产生显著影响，特别是通过降低断裂韧性。氢的降解通过纳米级的机制开始，并且在最终泄漏或组件断裂之前通常无法检测到。因此，计算技术正在开发，以提供更广泛的理解的现象和工程工具，预测材料的氢脆敏感性。这项工作提出了一种新的计算方法，其中密度泛函理论（DFT），纳米级实验和有限元（FE）建模相结合，相互关联，以提高氢致晶间开裂的理解的发展进行了初步研究。考虑了两种低角度和低重合晶界类型：Sigma（3）和Sigma（5）。密度泛函理论已被应用于研究的影响，增加数量的H原子上的这些晶界的结合强度在纯镍。这提供了之间的关系的H原子的数量（晶界的覆盖率）和内聚强度，这是进一步应用于内聚区有限元模拟的三角形纳米尺寸的断裂力学悬臂梁。为了验证该模型，这种标本将进行测试，实验与不原位电化学charging.Simulation结果表明，该模型是适合描述的晶界取向差和减少的结合能，由于氢的晶界倾向解理的综合效果。版权所有（C）2015，氢能出版物有限责任公司。由Elsevier Ltd.出版。保留所有权利。
Hydrogen (H) can have dramatic consequences on material properties, especially by reducing the fracture toughness. Degradation by H initiates through mechanisms at the nano-scale, and is normally not detectable prior to the final leakage or component fracture. Computational techniques are therefore being developed in order to provide both a wider understanding of the phenomenon and engineering tools for prediction of materials susceptibility toward hydrogen embrittlement. This work presents a preliminary study for the development of a novel computational approach in which density functional theory (DFT), nanoscale experiments and finite element (FE) modeling are combined and interrelated in order to improve the understanding of hydrogen induced intergranular cracking. Two low angle and low coincidence grain boundaries types have been considered: Sigma(3) and Sigma(5). Density Functional Theory has been applied to investigate the influence of an increasing number of H atoms on the cohesive strength of these grain boundaries in pure Nickel. This provided relations between the number of H atoms (coverage of the grain boundary) and the cohesive strength, which is further applied in cohesive zone FE modeling of a triangular nanometer sized fracture mechanics cantilever beam. For verification of the model such specimens will be tested experimentally both with and without in-situ electrochemical charging.The simulation results show that the model is suitable for describing the combined effect of grain boundary misorientation and the reduced cohesive energy due to hydrogen on the grain boundary propensity to cleave. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.