Hydrogen diffusion and trapping in a low copper 7xxx aluminium alloy investigated by Scanning Kelvin Probe Force Microscopy
Hydrogen diffusion and trapping in a low copper 7xxx aluminium alloy investigated by Scanning Kelvin Probe Force Microscopy
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DOI：
10.1016/j.msea.2017.08.119
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发表时间：
2017-10
期刊：
影响因子：
6.4
通讯作者：
L. Oger;M. Lafouresse;G. Odemer;L. Peguet;C. Blanc
中科院分区：
文献类型：
--
作者：
L. Oger;M. Lafouresse;G. Odemer;L. Peguet;C. Blanc
研究了7046铝合金的氢脆敏感性.在H2SO 4溶液中，对不同老化温度/时间偶的AA 7046样品进行阴极充电氢化。扫描开尔文探针力显微镜（SKPFM）结合全局氢量测量允许测量表观氢扩散系数（Dapp）：Dapp值随着时效持续时间的增加而减小归因于时效合金的硬化η'和η沉淀物的氢捕获。在25 °C下脱附后对充氢样品进行额外的SKPFM测量，并结合拉伸试验后断裂表面的SEM观察。结果表明，氢可以被困在晶界导致脆性沿晶断裂。然而，硬化沉淀物可以作为有效的捕获网站，并减少在晶界处的氢捕获。结论是AA 7046的HE的最关键的微观结构参数对应于晶界，而时效可以通过良好控制的沉淀来有助于提高合金的抗HE性。
The susceptibility to hydrogen embrittlement (HE) of the 7046 aluminium alloy (AA 7046) was investigated. Samples of AA 7046 corresponding to different ageing temperature/time couples were hydrogenated by cathodic charging in a H2SO4solution. Scanning Kelvin Probe Force Microscopy (SKPFM) combined with global hydrogen amount measurements allowed apparent hydrogen diffusion coefficients (Dapp) to be measured: the decrease of the Dappvalues with the increase of the ageing duration was attributed to hydrogen trapping by hardening η’ and η precipitates for the aged alloy. Additional SKPFM measurements were carried out on hydrogen charged samples after desorption at 25 °C and combined with SEM observations of the fracture surfaces after tensile tests. Results showed that hydrogen could be trapped at the grain boundaries leading to brittle intergranular fracture. However, hardening precipitates could act as efficient trapping sites and reduce hydrogen trapping at the grain boundaries. Conclusion is that the most critical microstructural parameters for HE of AA 7046 correspond to the grain boundaries while ageing could contribute to improve the resistance to HE of the alloy by a well-controlled precipitation.