Atomic Scale Studies of Heterophase Metallic Interfaces

异相金属界面的原子尺度研究

• 批准号: 9728986
• 负责人: David Seidman
• 金额: $ 60.32万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-02-01 至 2003-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9728986&HistoricalAwards=false
• 关键词: Atomic; Scale; Studies; Heterophase; Metallic

9728986 Seidman The principal thrust of this study is examination of segregation at well-characterized coherent and semicoherent heterophase interfaces developed in the same alloy system. Specimen preparation is achieved primarily via solid-state decomposition reactions or internal nitridation to produce precipitates with atomically clean interfaces. This is followed by low-temperature treatments to induce segregation of ternary or quaternary elements. Below a critical diameter the precipitates are coherent, while above this diameter they are semicoherent, allowing a study of segregation at either coherent or semicoherent interfaces. The highest resolution techniques available, including atom- probe field-ion and three-dimensional atom-probe microscopies, high-resolution and scanning transmission electron microscopies, and spatially resolved electron- energy-loss spectroscopy, are employed. Among the systems investigated, which include both interfaces of technological interest and `model' interfaces, are Al/Al3Sc (Mg) (an aerospace structural alloy); Al(Cu) and Cu(Sn or In) (interconnects for integrated circuits); Fe/Mo, Fe/Mo(V); alpha-Fe/molybdenum nitride (Sn); Au/Ni, with and without segregants. Theoretical modeling of heterophase interfaces addresses the interface structure and the properties of the segregants at the interfaces. The modeling employs ab initio density functional theory calculations, molecular dynamics and Monte Carlo simulations, and continuum elasticity theory. %%% Segregating atoms play a crucial role in the physical and mechanical properties of technologically significant heterophase metallic interfaces. Segregants are important for tailoring interfacial properties, e.g., by the introduction of selected microalloying solutes in controlled quantities. Control of the critical transition diameter from coherent to semicoherent precipitates is technologically important, as it determines the stability of the microstructure of the m aterial. ***

9728986 Seidman 这项研究的主要目的是检查在同一合金系统中开发的特征良好的相干和半相干异相界面的偏析。 样品制备主要通过固态分解反应或内部氮化产生具有原子级清洁界面的沉淀物来实现。 随后进行低温处理以引起三元或四元元素的偏析。 低于临界直径时，沉淀物是相干的，而高于该直径时，沉淀物是半相干的，从而可以研究相干或半相干界面处的偏析。 采用了可用的最高分辨率技术，包括原子探针场离子和三维原子探针显微镜、高分辨率和扫描透射电子显微镜以及空间分辨电子能量损失光谱。 在所研究的系统中，包括具有技术兴趣的界面和“模型”界面，其中包括 Al/Al3Sc (Mg)（一种航空航天结构合金）； Al(Cu) 和 Cu(Sn 或 In)（集成电路互连）；铁/钼、铁/钼(V)； α-Fe/氮化钼（Sn）； Au/Ni，有或没有偏析。 异相界面的理论建模解决了界面结构和界面偏析物的性质。 该建模采用从头算密度泛函理论计算、分子动力学和蒙特卡罗模拟以及连续弹性理论。 %%% 偏析原子对于技术上重要的多相金属界面的物理和机械性能起着至关重要的作用。 偏析对于调整界面性能非常重要，例如通过引入受控数量的选定微合金化溶质。 控制从共格析出物到半共格析出物的临界转变直径在技术上非常重要，因为它决定了材料微观结构的稳定性。 ***