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.***

0095381CHUNG这笔赠款介绍了围绕水分引起的金属间合金覆盖的基本问题，重点是（NI，FE）TI。尽管单个成分对水的反应性，但只要Fe浓度小于9 a/o，（Ni，Fe）Ti合金不受水分的影响。但是，在较高的铁浓度下，它们会严重拥抱水分。这需要对传统公认的水分诱导的金属层覆盖的机制进行详细的重新检查。也就是说，除了在金属间表面产生原子氢的水解离外，还需要哪些其他因素来产生水分引起的靠着？使用表面科学方法，本研究着眼于不同方向和Fe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原子氢，如果是的，则原子氢与金属间表面结合了多么强。对于改善理解最重要的是使用电子刺激的解吸对这些表面上氢的扩散性的定量确定。这些研究应提供必要的原子量表细节，以解释水分诱导的封闭，表面反应性和原子氢在金属合金中的迁移率之间的关系。 %% %%金属合金作为高温结构金属合金提供了希望。 一个潜在的问题是金属间与环境的反应性。 该赠款探讨了这个问题的一个方面。***