Deformation behaviour of an advanced nickel-based superalloy studied by neutron diffraction and electron microscopy
Deformation behaviour of an advanced nickel-based superalloy studied by neutron diffraction and electron microscopy
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DOI：
10.1016/j.actamat.2012.09.005
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发表时间：
2012-11-01
期刊：
影响因子：
9.4
通讯作者：
Preuss, Michael
中科院分区：
文献类型：
--
作者：
Grant, Benedict M. B.;Francis, Elisabeth M.;Preuss, Michael
研究了室温下拉伸载荷下多晶镍基高温合金的变形机制，该合金的γ′含量接近50 vol.%。为了确定γ′尺寸对变形机制的影响，建立了具有单峰γ′尺寸分布的模型显微组织。研究采用中子衍射原位加载实验、双点弹塑性自洽塑性模型和详细的死后电镜相结合的方法进行。显微镜工作还包括在500℃下应变的样品结果。在早期塑性变形期间，衍射数据表明伽马和伽马‘显示相同的弹性应变响应，表明在这个阶段，伽马’被位错切断，而不管伽马'的粒径大小。扫描电镜研究表明，在这三种微观结构中都存在大量剪切过程，从而支持了衍射实验得出的结论。随着材料进一步变形，在中（130 nm）和粗(230 nm) γ′微结构中观察到从γ′到γ′的弹性载荷传递，但在细(90 nm) γ′微结构中没有观察到。载荷传递可以通过假设Orowan环成为一种附加的工作变形模式来解释。透射电镜证实，在细γ′显微组织中，形变是由强耦合位错切割γ′引起的，而中、粗γ′显微组织则表现出额外的Orowan环的迹象。(C) 2012材料学报Elsevier Ltd.出版。版权所有。
Deformation mechanisms under tensile loading at room temperature have been studied in a polycrystalline nickel-based superalloy containing close to 50 vol.% gamma'. In order to identify the effect of gamma' particle size on deformation mechanisms, model microstructures with unimodal gamma' size distributions were developed. The investigations were carried out by combining in situ loading experiments using neutron diffraction and two-site elasto-plastic self-consistent plasticity modelling with detailed post-mortem electron microscopy. The microscopy work also includes results for samples strained at 500 degrees C. During early plastic deformation, the diffraction data demonstrate that gamma and gamma' display the same elastic strain response, indicating that at this stage gamma' is cut by dislocations regardless of the gamma' particle size. Scanning electron microscopy studies showed an abundance of shearing processes in all three microstructures, hence supporting the conclusions drawn from the diffraction experiment. As the material is further deformed, elastic load transfer from gamma to gamma' was observed in the medium (130 nm) and coarse (230 nm) gamma' microstructures but not in the fine (90 nm) gamma' microstructure. The load transfer can be explained by assuming that Orowan looping becomes an additional operative deformation mode. Transmission electron microscopy confirmed that in the fine gamma' microstructure deformation takes place by strongly coupled dislocations cutting the gamma', while the medium and coarse gamma' microstructures showed additional signs of Orowan looping. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.