The Role of Surface Reactions and Hydrogen Surface Diffusivity on the Environmental Embrittlement of (Ni,Fe)Ti Alloys

表面反应和氢表面扩散率对 (Ni,Fe)Ti 合金环境脆化的作用

• 批准号: 0095381
• 负责人: David Dunand
• 金额: $ 30.68万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-01 至 2006-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0095381&HistoricalAwards=false
• 关键词: Role; Surface; Reactions; Hydrogen; Diffusivity

0095381Chung This grant deals with the fundamental issues surrounding the moisture-induced embrittlement of intermetallic alloys with a focus on (Ni,Fe)Ti. In spite of the reactivity of individual components to water, (Ni,Fe)Ti alloys are not embrittled by moisture, as long as the Fe concentration is less than 9 a/o. However, they become severely embrittled by moisture at higher Fe concentrations. This calls for a detailed re-examination of the traditionally accepted mechanism of moisture-induced embrittlement of intermetallics. That is, in addition to the dissociation of water to produce atomic hydrogen on intermetallic surfaces, what other factors are required to produce moisture-induced embrittlement? Using a surface science approach, this study looks at the water vapor reactivity of single crystal (Ni,Fe)Ti surfaces of different orientations and Fe concentrations. The objective is to determine whether or not water dissociation to produce atomic hydrogen occurs, and, if so, how strongly the atomic hydrogen is bound to the intermetallic surface. Most important to improved understanding is a quantitative determination of the diffusivity of hydrogen on these surfaces using electron-stimulated desorption. These investigations should provide the necessary atomic scale details to explain the inter-relationships among moisture-induced embrittlement, surface reactivity, and mobility of atomic hydrogen in intermetallic alloys. %%%Intermetallic alloys offer promise as high temperature structural metal alloys. One potential problem is the reactivity of intermetallics with the environment. This grant explores one facet of this problem.***

0095381 Chung该授权涉及围绕金属间合金的湿致脆化的基本问题，重点是（Ni，Fe）Ti。尽管（Ni，Fe）Ti合金中的个别成分对水具有反应性，但只要Fe浓度小于9a/o，合金就不会因潮湿而脆化。然而，在较高的Fe浓度下，它们会因水分而变得严重脆化。这就要求对传统上公认的金属间化合物的湿致脆化机理进行详细的重新研究。也就是说，除了水的离解在金属间化合物表面上产生原子氢之外，还需要什么其他因素来产生湿致脆化？使用表面科学的方法，这项研究着眼于水蒸气反应性的单晶（Ni，Fe）Ti表面的不同取向和Fe浓度。目的是确定是否发生水离解产生原子氢，如果发生，原子氢与金属间化合物表面结合的强度如何。最重要的是，以提高理解是一个定量测定的扩散率的氢在这些表面上使用电子刺激解吸。这些调查应提供必要的原子尺度的细节，以解释之间的相互关系的水分引起的脆化，表面反应性，和流动性的原子氢在金属间化合物合金。%金属间化合物合金作为高温结构金属合金是有前途的。 一个潜在的问题是金属间化合物与环境的反应性。 这个问题的一个重要方面是：**