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The Study on the Effect of Nonstoichiometry on Thermal Equilibrium Defects in Intermetallic Compounds by Positron Annihilation

正电子湮灭非化学计量对金属间化合物热平衡缺陷影响的研究

基本信息

批准号：
02452230
负责人：
TANIGAWA Shoichiro
金额：
$ 3.78万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02452230/
关键词：
intermetallic compound positron annihilation nonstoichiometry

项目摘要

The effect of nonstoichiometry on thermal equilibrium defects in intermetallic compounds was studied by positron annihilation. The measurements of positron annihilation were carried out by means of the positrdn lifetime spectroscopy, the Doppler broadening spectroscopy, the two dimensional angular correlation of annihilation radiations and the slow positron analysis. The following results were obtained :(1) Defects introduced by nonstoichiometry in TiAl and TiAl_3 :The positron annihilation characteristics were measured as a function of the alloy compositions of the above alloys in their one phase region. As a result, it was found that the concentration of vacancy-type defects introduced by the nonstoichiometric composition is quite lower than the detection limit of the positron annihilation technique. This result clearly shows that the extra alloy elements form the antisite defects. From the thermal equilibrium experiment performed by the use of ^<48>V positon source, which was for the first time developed in the present research program, a greater num ber of divacancies were introduced in these intermetallic compounds as compared with In pure metals.(2) Determination of three dimensional momentum space density of electrons in beta'-AgZn :By the measurements of 2D-ACAR spectra with different crystal orientations followed the image reconstruction technique, the three dimensional momentum space density of electrons in beta'-AgZn was determined. The experimentally determined density coincides well with the theoretically expected one. In this case, the extra alloy elements also occupy the antisite lalttice points.In addition, the determination of thd densities in NiAl, Ni_3Al and NbSe_2 was carried out successfully.

用正电子湮没方法研究了非化学计量比对金属间化合物热平衡缺陷的影响。用正电子寿命谱、多普勒展宽谱、湮没辐射的二维角关联和慢正电子分析等方法对正电子湮没进行了测量。（1）TiAl和TiAl_3中的非化学计量缺陷：在单相区测量了正电子湮没特性随合金成分的变化。结果发现，由非化学计量组成引入的空位型缺陷的浓度远低于正电子湮没技术的检测极限。这一结果清楚地表明，多余的合金元素形成反位缺陷。利用<48>本研究计划中首次研制的~（40）V正子源进行的热平衡实验表明，在这些金属间化合物中引入的双空位比纯In金属中的多。(2)β ′-AgZn中电子的三维动量空间密度的测定：通过测量不同晶向的二维ACAR谱，并结合图像重建技术，测定了β ′-AgZn中电子的三维动量空间密度。实验测定的密度与理论预期的密度吻合得很好。此外，还成功地测定了NiAl、Ni_3Al和NbSe_2的密度。