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.***

本基金主要研究（Ni,Fe）Ti等金属间合金湿致脆的基本问题。尽管个别成分对水有反应性，但只要铁浓度低于9 a/o， （Ni,Fe）Ti合金就不会被水分脆化。然而，在较高的铁浓度下，它们会被水分严重脆化。这就要求对传统上公认的湿致金属间化合物脆化机制进行详细的重新研究。也就是说，除了水在金属间表面解离产生氢原子外，还需要哪些其他因素才能产生湿致脆？利用表面科学方法，本研究观察了不同取向和不同铁浓度的单晶（Ni,Fe）Ti表面的水蒸气反应性。目的是确定是否发生水解离产生氢原子，如果发生，原子氢与金属间表面的结合有多强。最重要的是利用电子刺激解吸来定量测定氢在这些表面上的扩散率。这些研究应该提供必要的原子尺度细节来解释金属间合金中水分引起的脆化、表面反应性和氢原子迁移率之间的相互关系。金属间合金作为高温结构金属合金具有广阔的应用前景。一个潜在的问题是金属间化合物与环境的反应性。这项拨款探索了这个问题的一个方面