慢正电子束流技术在金属/合金微观缺陷研究中的应用

正电子湮没谱学技术是研究材料微观结构非常有效的一种核谱学分析方法, 主要用于获取材料内部微观结构的分布信息, 特别是微观缺陷结构及其特性等传统表征方法难以获取的微观结构信息. 近年来, 在慢正电子束流技术快速发展的基础上, 正电子湮没谱学技术在薄膜材料表面和界面微观结构的研究中得到了广泛应用. 特别是该技术对空位型缺陷的高灵敏表征能力, 使其在金属/合金材料表面微观缺陷的形成机理、缺陷结构特性及其演化行为等研究方面具有独特的优势. 针对材料内部微观缺陷的形成、演化机理以及缺陷特性的研究, 如缺陷的微观结构、化学环境、电子密度和动量分布等, 正电子湮没谱学测量方法和表征分析技术已经发展成熟. 而能量连续可调的低能正电子束流, 进一步实现了薄膜材料表面微观结构深度分布信息的实验表征. 本文综述了慢正电子束流技术应用研究的最新进展, 主要围绕北京慢正电子束流装置在金属/合金材料微观缺陷的研究中对微观缺陷特性的表征和表面微观缺陷演化行为的应用研究成果展开论述.

Applications and progress of slow positron beam technique in the study of metal/alloy microdefects

In recent decades, the positron annihilation spectroscopy technique has been used to characterize the microdefects of materials due to its advantages of non-destruction and high sensitivity on an atomic level. Positron annihilation spectroscopy technique is widely used in the microstructure study of thin film material surface and interface due to the rapid development of the slow positron beam technology. The slow positron beam technique can provide depth distribution information about material surface microstructure. Therefore, it is widely used to study the distributed defect concentrations in crystalline materials and the properties of thin films, surfaces and interfaces of layered materials. This article summarizes the slow positron beam technique applications and progress in the study of metal alloy materials. Firstly, this article introduces the slow positron beam technology development and application research achievement in detail. Secondly, it provides how to acquire the slow positron beam, introduces some kinds of and the principles of experimental measurements, and the major methods include Doppler bradening spectroscopy, coincidence Doppler broadening and PL. Thirdly, according to the defects induced by different ways, the latest experimental results about the material internal microdefect formation mechanism, evolution mechanism, defect feature research, such as microstructure, chemical environment, electron density and momentum distribution are introduced. The methods of inducing defects mainly include irradiation, physical deformation and chemical corrosion. Particles irradiation can be classified as four parts according to the different types of particles. In addition, monolayer and multilayer thin films have also been summarized. Finally, the new technique of thermal desorption spectroscopy and experimental measurements of age-momentum correlation are proposed. We can know that positron annihilation spectroscopy technology is a very special and effective nuclear spectroscopy analysis method in material microstructure study, and the slow positron beam technique makes it possible to study the depth distribution information about the thin film material surface microstructure. There is no doubt that this technique will play a huge role in the progress of material science and the creation of industrial material.