Atomic-resolution evaluation of microsegregation and degree of atomic order at antiphase boundaries in Ni50Mn20In30 Heusler alloy
Atomic-resolution evaluation of microsegregation and degree of atomic order at antiphase boundaries in Ni50Mn20In30 Heusler alloy
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DOI：
10.1016/j.actamat.2016.09.035
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发表时间：
2017-01-01
期刊：
影响因子：
9.4
通讯作者：
Kainuma, R.
中科院分区：
文献类型：
--
作者：
Niitsu, K.;Minakuchi, K.;Kainuma, R.
通过多层模拟、大角度环状暗场扫描电子显微镜(HAADF-STEM)、X射线衍射图Rietveld分析、能谱分析和修正的Bragg Williams Gorsky计算，研究了Ni50Mn20In30 Heusler合金热致反相界附近的原子排列和微观偏析。对原子分辨率的HAADF-STEM图像的强度分析表明，反相界发生了180度的几何相移，伴随着原子有序度的衰减和In的富集化。能谱分析表明，In在反相界中心的丰度高达2.7at.%，与用改进的Bragg Williams-Gorsky计算得到的L2(1)和B2相的Gibbs能量曲线的平行切线定律给出的值(1.0-1.8at.%)相当。这表明微观偏析发生在反相界面上，并且基本上可以在局部热力学平衡的框架内被理解。(C)2016 Acta Materialia Inc.由Elsevier Ltd.出版。这是一篇CC By-NC ND许可证下的开放获取文章。
The atomic arrangement and microsegregation in the vicinity of thermally induced antiphase boundaries in a Ni50Mn20In30 Heusler alloy are investigated through multislice simulations, high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction pattern Rietveld analysis, energy-dispersive X-ray spectroscopy, and modified Bragg Williams Gorsky calculations. Intensity analysis of atomic-resolution HAADF-STEM images revealed that a 180 degrees geometrical phase shift occurred across the antiphase boundaries, accompanied by a decay in the degree of atomic order and an enrichment of In. Energy-dispersive (X-ray) spectroscopy analysis revealed an In enrichment as high as 2.7 at.% at the center of the antiphase boundaries, comparable to that (1.0-1.8 at.%) suggested by the parallel tangent law for the Gibbs energy curves of the L2(1) and B2 phases using the modified Bragg Williams-Gorsky calculation. This suggests that microsegregation occurs at the antiphase boundaries and can be understood basically within the framework of the local thermodynamic equilibrium. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY-NC ND license.