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场离子显微镜(FIM)原子探针(AP)已广泛应用于材料科学及表面物理许多领域。本文简要介绍FIM—AP基本原理和仪器结构及本实验室将FIM—AP应用于材料微观结构研究取得部分结果。FIM将试样放大近二百万倍可直接观察到固体表面单个原子,AP能检测单个原子。仪器是在瑞典查尔摩斯工业大学帮助下与科学院沈阳科仪厂及北京科仪厂共同研制。FIM—AP应用于材料微观结构研究(1)钨晶体表面结构观察:图1a是W(011)为中心极二次对称像,这像反映了W原子在针尖表面上排列,相距3.16A两个W原子分开很清楚,图1b是和立方晶体极射投影图对照并标出了钨场离子像上的主要晶带轴和面指数。(2)掺杂灯丝晶界结构观察:钨丝中掺杂微量K—Si—Al元素可提高灯丝高温蠕变性能,但对掺杂元素引起灯丝结构变化机理并不十分清楚。图2a
Field ion microscope (FIM) atomic probes (APs) have been widely used in many fields of material science and surface physics. This article briefly introduces the basic principles of FIM-AP and instrument structure and the laboratory to FIM-AP applied to the microstructure of materials obtained some results. FIM magnifies the sample almost two million times to directly observe a single atom on a solid surface. The AP can detect a single atom. The instrument was developed with the help of the Swedish Chalmers University of Technology and Shenyang Branch Scientific Instrument Factory and Beijing Branch Instrument Factory. FIM-AP is used to study the microstructure of materials. (1) Observation of the surface structure of tungsten crystal: Figure 1a shows the symmetric secondary symmetric image of W (011). This image reflects the arrangement of W atoms on the surface of the needle tip, The W atoms are clearly separated, and Figure 1b is in contrast to the cubic crystal projection and shows the major band axes and surface indices on the tungsten field ion image. (2) Observation of the grain boundary structure of doped filaments: The doping of K-Si-Al element in tungsten filament can improve the creep property of filament, but the mechanism of filament structure change caused by doping element is not very clear. Figure 2a