氢影响下纳米晶体晶界滑移和晶界三叉点裂纹形核模型

赵可可; 朱云蝶; 张吉鼎; 江晓禹

doi:10.21656/1000-0887.440257

氢影响下纳米晶体晶界滑移和晶界三叉点裂纹形核模型

doi: 10.21656/1000-0887.440257

西南交通大学力学与航空航天学院，成都 611756

基金项目:

国家自然科学基金 11472230

详细信息

作者简介:
赵可可(1996—)，男，硕士(E-mail: zkk4255@163.com)

通讯作者:
江晓禹(1965—)，男，教授，博士，博士生导师(通讯作者. E-mail: xiaoyujiang8@sina.com)

中图分类号: O346
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- 被引次数: 0
出版历程
- 收稿日期: 2023-08-22
- 修回日期: 2024-02-01
- 刊出日期: 2024-07-01

Grain Boundary Slip and a Grain Boundary Triple Junction Crack Nucleation Model for Nanocrystals Under the Influence of Hydrogen

School of Mechanics and Aerospace Engineering, Southwest Jiaotong University，Chengdu 611756, P.R. China

摘要

摘要: 在远场均匀拉伸载荷下，裂纹尖端会产生应力集中，与裂纹尖端相邻的晶界会承受较大的切应力，此切应力会导致晶界滑移. 该文研究了氢和纳米晶界滑移对晶界裂纹形核、临界应力强度因子以及屏蔽效应的影响. 应用连续分布位错方法给出了模型的理论解. 结果表明：由于位错在晶界三叉点和滑移带尖端处的塞积，楔形裂纹会优先沿着晶界三叉点DC方向和晶界BD向上萌生，而且氢会使得裂纹萌生的总能量降低，氢浓度每增加1%，萌生最稳定裂纹的总能量大约降低1.86%. 虽然晶界滑移会使得裂纹尖端的临界应力强度因子和屏蔽效应增大, 但是氢使得临界应力强度因子降低. 最后根据弱键理论，研究了氢对表面能的影响，氢浓度每增加1%，表面能降低5%. 这一理论工作提供了氢和晶界滑移对材料微观断裂力学的新信息，有助于解释金属断裂的微观机理.
- 晶界滑移 /
- 晶界三叉点 /
- 裂纹 /
- 氢 /
- 临界应力强度因子 /
- 屏蔽效应
Abstract: Under the far-field uniform tensile load, the crack tip will generate stress concentration, and the grain boundary adjacent to the crack tip will bear large shear stresses to cause nanograin boundary slip. The effects of hydrogen and nanoboundary slip on the crack nucleation, the critical stress intensity factor and the shielding action were investigated. The theoretical solution of the model was given with the continuous distributed dislocation method. The results show that, the wedge cracks preferentially germinate along direction DC of the grain boundary triple junction and grain boundary BD due to the plugging of the dislocation at the grain boundary triple junction and the tip of the slip plane. Moreover, hydrogen decreases the total energy of crack initiation. When hydrogen concentration increases by 1%, the total energy of the most stable crack initiation will decrease by about 1.86%. Although the grain boundary slip increases the critical stress intensity factor and the shielding action at the crack tip, hydrogen will decrease the critical stress intensity factor. Finally, according to the hydrogen enhanced decohesion (HEDE) theory, the influence of hydrogen on surface energy was studied. With every 1% increase of the hydrogen concentration, the surface energy will decrease by 5%. This theoretical work provides new information on the microscopic fracture mechanics of materials caused by hydrogen and grain boundary slip, and helps to explain the microscopic mechanism of metal fracture.
- grain boundary slip /
- grain boundary triple junction /
- crack /
- hydrogen /
- critical stress intensity factor /
- shielding effect

HTML全文

图 1 主裂纹尖端位错发射与晶界滑移导致纳米裂纹萌生的过程示意图

注为了解释图中的颜色，读者可以参考本文的电子网页版本，后同.

Figure 1. Schematic diagram of the initiation process of a nanocrack caused by dislocation emission and grain boundary slip at the main crack tip

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图 2 位错数目随角度β和外加应力的变化

Figure 2. The numbers of dislocations varying with angle β and the applied stress

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图 3 裂纹尖端屏蔽效应和位错发射数目随外加载荷的变化关系

Figure 3. Relationships between the emission numbers of crack tip dislocations and shielding effects with applied loads

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图 4 沿不同晶界的裂纹萌生总能量和氢对裂纹萌生总能量的影响

Figure 4. The total energy of crack initiation along different grain boundaries and the effects of hydrogen on the total energy of crack initiation

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图 5 不同位置处裂纹萌生的总能量和氢对裂纹萌生总能量的影响

Figure 5. The total energy of crack initiation at different locations and the effects of hydrogen on the total energy of crack initiation

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图 6 临界应力强度因子随外加载荷的变化

Figure 6. Changes of the critical stress intensity factor with the applied load

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