Department of Metallurgical & Materials Engineering, University of Alabama, College of Engineering, Tuscaloosa, AL 35487, USA.
Ultramicroscopy. 2011 May;111(6):464-8. doi: 10.1016/j.ultramic.2011.01.001. Epub 2011 Jan 19.
A methodology for determining the optimal voxel size for phase thresholding in nanostructured materials was developed using an atom simulator and a model system of a fixed two-phase composition and volume fraction. The voxel size range was banded by the atom count within each voxel. Some voxel edge lengths were found to be too large, resulting in an averaging of compositional fluctuations; others were too small with concomitant decreases in the signal-to-noise ratio for phase identification. The simulated methodology was then applied to the more complex experimentally determined data set collected from a (Co(0.95)Fe(0.05))(88)Zr(6)Hf(1)B(4)Cu(1) two-phase nanocomposite alloy to validate the approach. In this alloy, Zr and Hf segregated to an intergranular amorphous phase while Fe preferentially segregated to a crystalline phase during the isothermal annealing step that promoted primary crystallization. The atom probe data analysis of the volume fraction was compared to transmission electron microscopy (TEM) dark-field imaging analysis and a lever rule analysis of the volume fraction within the amorphous and crystalline phases of the ribbon.
开发了一种使用原子模拟器和具有固定两相组成和体积分数的模型系统来确定纳米结构材料中相阈值的最佳体素大小的方法。体素大小范围由每个体素内的原子数带隙。发现一些体素边缘长度太大，导致成分波动的平均化；另一些则太小，导致相位识别的信噪比降低。然后将模拟方法应用于更复杂的实验确定的数据集中，该数据集来自（Co(0.95)Fe(0.05))(88)Zr(6)Hf(1)B(4)Cu(1)两相纳米复合材料合金，以验证该方法。在该合金中，Zr 和 Hf 偏析到晶间非晶相，而 Fe 在促进初级结晶的等温退火步骤中优先偏析到晶相。体积分数的原子探针数据分析与透射电子显微镜（TEM）暗场成像分析以及带材中非晶相和晶相的体积分数的杠杆规则分析进行了比较。
