Oscillatory Surface Segregations

该建议使用飞行时间原子探针场离子显微镜 （亚太经社会），以检查与 在金属合金中具有表面偏析。 组成变化 在铂-铑，铂-金， 铂-镍和铂-镍合金在一个 10到15个原子层的深度。 这些标本是以 具有沉积在尖端表面上的薄膜的发射器尖端， 平行于尖端发射器表面的界面。 的格局 化学分布被确定为以下深度的函数 表面和相关的合金行为， 化学吸附和有序-无序相变。 %%% 重要的是要了解元素偏析在 金属合金的表面，因为表面成分会影响 潜在的应用，需要的性质，如氧化 电阻、化学吸附、催化行为和耐磨性。

This proposal uses time of flight atom-probe field ion microscopy (APFIM) to examine the near-surface composition profiles associated with surface segregation in metal alloys. Composition variations in the near surface layers of platinum-rhodium, platinum-gold, platinum-nickel, and molybdenum-rhenium alloys are measured over a depth of 10 to 15 atomic layers. The specimens are in the form of emitter tips with thin films deposited on the tip surface and interfaces parallel to the tip emitter surface. The pattern of chemical distribution is determined as a function of depth below the surface and correlated with alloy behavior such as chemisorption and order-disorder phase transformations. %%% It is important to understand the elemental segregation at the surface of metal alloys because surface composition can affect potential applications that require properties such as oxidation resistance, chemisorption, catalytic behavior, and wear resistance.