Oscillatory Surface Segregations

这项建议使用飞行时间原子探针场离子显微镜(APFIM)来研究金属合金中与表面偏析相关的近表面成分分布。在10到15个原子层的深度内，测量了铂-铑、铂金-金、铂-镍和钼-Re合金近表层的成分变化。样品为发射极尖端的形式，薄膜沉积在尖端表面，界面平行于尖端发射极表面。化学分布模式是表面下深度的函数，并与合金的化学吸附和有序-无序相变等行为相关联。%了解金属合金表面的元素偏析很重要，因为表面成分可能会影响需要抗氧化、化学吸附、催化行为和耐磨性等性能的潜在应用。

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.