Nanoscale lead and noble gas inclusions in aluminum: Structures and properties
Nanoscale lead and noble gas inclusions in aluminum: Structures and properties
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铝中纳米级铅和稀有气体夹杂物：结构和性能
DOI：
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发表时间：
2004
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通讯作者：
U. Dahmen
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文献类型：
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作者：
E. Johnson;H. H. Andersen;U. Dahmen
透射电子显微镜已被用于铝中铅和稀有气体的纳米级夹杂物的结构和物理表征。当夹杂物尺寸接近纳米尺度时，它们的许多性质被认为偏离了本体中的类似性质，并且在大多数情况下，偏差将随着夹杂物尺寸的减小而增大。铅和稀有气体与铝的二元合金的特征在于极低的互溶度，因此，夹杂物将作为嵌入铝基体中的实际上纯的组分存在。此外，在室温和高于室温下铝中的热空位迁移率足够高，以适应与夹杂物相关的体积应变，从而导致几乎无应变的晶体。夹杂物与铝基体呈平行立方体排列生长，呈立方八面体形状，直接反映了界面能的各向异性。晶界中的夹杂物可以具有单晶或双晶形态，这可以从广义的Wulff分析（如矢量结构）中解释。夹杂物具有多种纳米尺度特征，如高拉普拉斯压力、熔化过程中的尺寸依赖性过热、偏离武尔夫形状的神奇尺寸效应、边缘能量的形状依赖性等。所有这些效应都通过TEM利用常规成像条件和高分辨率条件结合高温原位分析进行了观察和监测。Microsc. Res. Tech. 64：356-372，2004.© 2004 Wiley利斯公司
Transmission electron microscopy has been used for structural and physical characterization of nanoscale inclusions of lead and noble gases in aluminum. When the inclusion sizes approach nanoscale dimensions, many of their properties are seen to deviate from similar properties in bulk and in most cases the deviations will increase as the inclusion sizes decrease. Binary alloys of lead and noble gases with aluminum are characterized by extremely low mutual solubilities and inclusions will, therefore, exist as practically pure components embedded in the aluminum matrix. Furthermore, the thermal vacancy mobility in aluminum at and above room temperature is sufficiently high to accommodate volume strains associated with the inclusions thus leading to virtually strain free crystals. The inclusions grow in parallel cube alignment with the aluminum matrix and have a cuboctahedral shape, which reflects directly the anisotropy of the interfacial energies. Inclusions in grain boundaries can have single crystalline or bicrystalline morphology that can be explained from a generalized Wulff analysis such as the ξ‐vector construction. The inclusions have been found to display a variety of nanoscale features such as high Laplace pressure, size‐dependent superheating during melting, deviations from the Wulff shape displaying magic size effects, a shape dependence of edge energy, and so on. All these effects have been observed and monitored by TEM using conventional imaging conditions and high‐resolution conditions in combination with in‐situ analysis at elevated temperatures. Microsc. Res. Tech. 64:356–372, 2004. © 2004 Wiley‐Liss, Inc.