Deformation and Failure of Nanocrystalline Metals

纳米晶金属的变形和失效

• 批准号: 9980213
• 负责人: Fereshteh Ebrahimi
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9980213&HistoricalAwards=false
• 关键词: Deformation; Failure; Nanocrystalline; Metals

9980213EbrahimiThe aims of this project are to evaluate experimentally the mechanical behavior of FCC and BCC nanocrystalline metals and to develop mechanistic deformation models for various grain size regimes. The deformation and failure mechanisms of pure Ni, Ni-Cu and Fe-Ni alloys are studied by characterizing yielding, strain hardening, plastic instability, and fracture as functions of temperature and strain rate. Analysis of such results in conjunction with detailed microstructural analyses should lead to a systematic understanding of the operating mechanisms. Some alloy variations are examined. When copper is added to nickel the stacking fault energy is reduced significantly, thereby affecting the generation and accumulation of dislocations. A small increase in the concentration of nickel in Fe-Ni alloys results in a change of crystal structure from BCC to FCC. In this way, the effect of crystal structure can be investigated at comparable compositions. %%%Despite an expansion of research in the past decade on nanostructured metallic alloys, there have been few experimental studies that investigate the mechanical properties of these materials. Metallic solids with crystallite sizes less than approximately 100nm are referred to as nanocrystalline metals. These materials have attractive properties, including very high strength levels. The outcome of this research will contribute to the development of metallic structures that are as strong as hardened steels (700 - 1800 MPa) but have better physical properties (e.g. magnetic properties) and superior corrosion resistance.***

这个项目的目的是从实验上评估面心立方和体心立方纳米晶金属的力学行为，并开发不同晶粒度区域的力学变形模型。通过研究纯镍、镍铜和铁镍合金的屈服、应变硬化、塑性失稳和断裂随温度和应变速率的变化，研究了纯镍、镍铜和铁镍合金的变形和破坏机制。结合详细的微观结构分析对这些结果进行分析，应有助于对运作机制有系统的了解。对一些合金的变化进行了考察。当铜添加到镍中时，层错能显著降低，从而影响位错的产生和积累。Fe-Ni合金中镍含量的小幅增加会导致晶体结构由体心立方向面心立方转变。通过这种方法，可以在可比较的成分下研究晶体结构的影响。尽管在过去的十年里，对纳米结构金属合金的研究有所扩大，但很少有实验研究来研究这些材料的机械性能。微晶尺寸小于约100 nm的金属固体称为纳米晶金属。这些材料具有诱人的特性，包括非常高的强度水平。这项研究的结果将有助于开发与淬火钢一样坚固的金属结构(700-1800兆帕)，但具有更好的物理性能(例如磁性)和优异的耐腐蚀性。