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Quantitative microanalysis in the analytical electron microscope and its application to the construction of alloy phase diagrams.

分析电子显微镜中的定量微分析及其在合金相图构建中的应用。

基本信息

批准号：
62460195
负责人：
NEMOTO Minoru
金额：
$ 5.31万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

This study is concerned with the quantitative microanalysis of thin samples in the analyti-cal electron microscope equipped with an energy dispersive spectrometer and its application to the construction of phase diagrams in Ni-based alloys.For accurate and precise quantification, it is important to use the k-factors which are determined experimentally rather than calculated theoretically. This is because the theoretical equation cannot describe changes in the sensitivity for X-ray detection. The X-ray absorption in the sample leads to a significant error in quntification but this can be corrected simply by using the extrapolation method and the diferential X-ray absorption method, both of which do not require measurement of the thickness in analysed regions.An experiment shows that the depth distribution of X-ray production is almost constant across the thickness of Ni thin sample. Thus, this effect is considered to be negligible on the quantification Ni-base alloys.Because the formation of surface layers which are rich in X-element in Al-X (X=Si,Cu,Ag) alloys, an error may be introduced in the quantification particularly for thinner regions. The effects of such surface layer can be reduced by ion-milling or by the use of the extrapolation method.Determination of the Ni-Al-Ta ternary phase diagrams at lower temperaures results that the gamma/gamma' two phase area expands to the region of higher Ni concentration. This is different from earlier results obtained by EPMA method in SEM. It is found that, in the gamma/gamma' two phase regions of the Ni-Al-Mo ternary system, Mo is more partitioned into gamma' phase than gamma phase when the total amount of Mo is small. However, with an increasing addition of Mo, partitioning behavior is reversed. Mo is more contained in gamma phase than gamma' phase. Similar behavior is observed for Ta in the Ni-Al-Ta ternary system.

本文研究了在分析电子显微镜上对薄样品进行定量分析，并将其应用于镍基合金相图的绘制。为了精确定量，必须使用实验测定的k因子，而不是理论计算的k因子。这是因为理论方程不能描述X射线检测灵敏度的变化。样品中的X射线吸收导致了很大的定量误差，但这可以用外推法和差分X射线吸收法简单地校正，这两种方法都不需要测量分析区的厚度，实验表明，在Ni薄样品的厚度上，X射线产生的深度分布几乎是恒定的。由于Al-X（X=Si，Cu，Ag）合金中形成了富X元素的表面层，特别是在较薄的区域，可能会在定量中引入误差。用离子铣削或外推法可消除这种表面层的影响，测定了较低温度下Ni-Al-Ta三元相图，发现γ/γ ′两相区向高Ni浓度区扩展。这与以往在SEM中用EPMA方法得到的结果不同。结果表明，在Ni-Al-Mo三元系的γ/γ '两相区，当Mo总量较小时，Mo更多地分配到γ'相中。然而，随着Mo添加量的增加，分配行为发生逆转。Mo在γ相中的含量高于γ ′相中的含量。Ta在Ni-Al-Ta三元系中也有类似的行为。