Hornbuckle B C, Kapoor M, Thompson G B
The University of Alabama, Department of Metallurgical and Materials Engineering, Tuscaloosa, AL, 35487 USA.
The University of Alabama, Department of Metallurgical and Materials Engineering, Tuscaloosa, AL, 35487 USA.
Ultramicroscopy. 2015 Dec;159 Pt 2:346-53. doi: 10.1016/j.ultramic.2015.03.003. Epub 2015 Mar 7.
A proximity histogram or proxigram is the prevailing technique of calculating 3D composition profiles of a second phase in atom probe tomography. The second phase in the reconstruction is delineated by creating an isoconcentration surface, i.e. the precipitate-matrix interface. The 3D composition profile is then calculated with respect to this user-defined isoconcentration surface. Hence, the selection of the correct isoconcentration surface is critical. In general, the preliminary selection of an isoconcentration value is guided by the visual observation of a chemically partitioned second phase. However, in low-chemical -partitioning systems, such a visual guide is absent. The lack of a priori composition information of the precipitate phase may further confound the issue. This paper presents a methodology of selecting an appropriate elemental species and subsequently obtaining an isoconcentration value to create an accurate isoconcentration surface that will act as the precipitate-matrix interface. We use the H-phase precipitate in the Ni-Ti-Hf shape memory alloy as our case study to illustrate the procedure.
邻近直方图或邻近图是原子探针断层扫描中计算第二相三维成分分布的主流技术。重建中的第二相通过创建等浓度表面来描绘，即析出物 - 基体界面。然后相对于这个用户定义的等浓度表面计算三维成分分布。因此，选择正确的等浓度表面至关重要。一般来说，等浓度值的初步选择是通过对化学分区的第二相进行视觉观察来指导的。然而，在低化学分区系统中，缺乏这样的视觉指导。析出相先验成分信息的缺失可能会进一步使问题复杂化。本文提出了一种选择合适元素种类并随后获得等浓度值以创建准确等浓度表面的方法，该表面将作为析出物 - 基体界面。我们以镍钛铪形状记忆合金中的H相析出物为例来说明该过程。
