Chalmers University of Technology, Gothenburg, Sweden.
Ultramicroscopy. 2011 May;111(6):652-8. doi: 10.1016/j.ultramic.2011.01.015. Epub 2011 Jan 19.
Atom probe tomography (APT) allows near atomic scale compositional- and morphological studies of, e.g. matrix, precipitates and interfaces in a wide range of materials. In this work two Ni-base superalloys with similar compositions, Alloy 718 and its derivative Allvac 718Plus, are subject for investigation with special emphasis on the latter alloy. The structural and chemical nuances of these alloys are important for their properties. Of special interest are grain boundaries as their structure and chemistry are important for the materials' ability to resist rapid environmentally induced crack propagation. APT has proved to be suitable for analyses of these types of alloys using voltage pulsed APT. However, for investigations of specimens containing grain boundaries and other interfaces the risk for early specimen fracture is high. Analyses using laser pulsing impose lower electrical field on the specimen thereby significantly increasing the success rate of investigations. Here, the effect of laser pulsing was studied and the derived appropriate acquisition parameters were then applied for microstructural studies, from which initial results are shown. Furthermore, the influence of the higher evaporation field experienced by the hardening γ' Ni(3)(Al,Nb) precipitates on the obtained results is discussed.
原子探针层析技术（APT）允许对各种材料中的基体、析出物和界面等进行近原子尺度的成分和形态研究。在这项工作中，我们对两种具有相似成分的镍基高温合金——Alloy 718 及其衍生的 Allvac 718Plus——进行了研究，特别关注后者。这些合金的结构和化学细微差别对它们的性能很重要。晶界尤其受到关注，因为它们的结构和化学性质对材料抵抗快速环境诱发裂纹扩展的能力至关重要。APT 已被证明适用于使用电压脉冲 APT 对这些类型的合金进行分析。然而，对于含有晶界和其他界面的样品的分析，早期样品断裂的风险很高。使用激光脉冲进行分析会对样品施加较低的电场，从而大大提高分析的成功率。在这里，研究了激光脉冲的影响，并应用由此得出的适当采集参数进行了微观结构研究，展示了初始结果。此外，还讨论了较硬的γ' Ni(3)(Al,Nb)析出物经历的较高蒸发场对获得结果的影响。
