Novel Metastable Phases and Kinetics Studies in Transition Metals and Alloys under Terapascal Pressures

兆帕压力下过渡金属和合金的新型亚稳态相和动力学研究

• 批准号: 1608682
• 负责人: Yogesh Vohra
• 金额: $ 38.33万
• 依托单位: University of Alabama at Birmingham
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1608682&HistoricalAwards=false
• 关键词: Novel; Metastable; Phases; Kinetics; Studies

Non-technical AbstractSeveral elements in the periodic table when subjected to external high-pressure and high-temperature adapt novel structural modifications leading to improvements in their physical and mechanical properties. In certain cases, these novel crystal modifications with enhanced physical and mechanical properties can be retained after removal of pressure resulting in potential industrial applications. The conversion of graphitic carbon into diamond by application of high-pressure and high-temperature is a prime example of this research. This research program will carry out high-pressure high-temperature studies on transition metals and alloys that are widely used in aerospace, biomedical, and nuclear industry. This research is enabled by advances in the generation of ultra high pressure up to ten million atmospheres in the laboratory using an innovative design of diamond anvils in high pressure devices. This advance in high pressure technique coupled with very bright sources of x-rays allows us to probe changes in crystal structures so we can construct stability maps for various crystal structures at elevated pressures and temperatures. These stability maps will allow researchers to design new strategies to synthesize these materials in bulk form for industrial applications. The project participants will receive extensive research training at the premier national facilities employing x-ray synchrotron radiation in materials research leading to a pipeline of trained scientific workforce in high pressure science. Our long-term partnership with the Historically Black Colleges and Universities in the southeastern region will ensure participation of underrepresented minority groups in this research program. Technical AbstractThe study of transition metals under extreme conditions has seen rapid progress in the last few years with the attainment of near Terapascal (1 TPa = 1000 GPa) static pressures using two-stage diamond micro-anvils along with the development of millisecond x-ray diffraction techniques using fast detectors at the synchrotron facilities. At the University of Alabama at Birmingham, a novel method for the fabrication of two-stage diamond micro-anvils using a chemical vapor deposition technique has been developed. In addition, rapid pressure and temperature changes can be applied to samples using piezoelectric drivers (dynamic diamond anvil cells) and boron-doped heating anvils, thus providing ideal tools to study phase transformations and transformation kinetics in transition metals and alloys under extreme conditions. In this study, a focus is on transformation kinetics of hexagonal close-packed (hcp-phase) to simple hexagonal (omega-phase) transformation and from omega-phase to body-centered cubic (bcc-phase) in Titanium-Vanadium (Ti-V) and Hafnium-Tantalum (Hf-Ta) alloys. The goal is to establish the occurrence of other novel phases like the orthorhombic modifications (gamma, delta, and eta phases) in early transition metals and alloys under hydrostatic (neon pressure medium) and non-hydrostatic (no pressure medium) conditions. In Osmium (Os) metal, structural anomalies have been observed at 150 GPa and 440 GPa at ambient temperature that warrant further investigations at elevated temperatures. It is anticipated that most of the early members of the transition metal series are converted in to nearly pure d-band metals as s-electron levels move above the Fermi-level at extreme pressures. This study would provide crystal structure data and pressure-volume data for this unique electronic state of transition metals and alloys under extreme conditions for direct comparison with the theoretical models.

非技术摘要元素周期表中的几种元素在受到外部高压和高温时会发生新的结构变化，从而改善其物理和机械性能。在某些情况下，这些具有增强的物理和机械性能的新型晶体修饰可以在去除压力后保留，从而产生潜在的工业应用。通过高压和高温将石墨碳转化为金刚石是这项研究的一个典型例子。该研究项目将对广泛应用于航空航天、生物医学和核工业的过渡金属和合金进行高压高温研究。这项研究是通过在实验室中使用高压设备中的金刚石砧的创新设计来产生高达一千万个大气压的超高压而得以实现的。高压技术的进步与非常明亮的 X 射线源相结合，使我们能够探测晶体结构的变化，从而可以构建各种晶体结构在高压和高温下的稳定性图。这些稳定性图将使研究人员能够设计新的策略来合成这些材料以用于工业应用。项目参与者将在主要的国家设施中接受广泛的研究培训，在材料研究中使用 X 射线同步加速器辐射，从而培养出一批训练有素的高压科学科学队伍。我们与东南部地区历史悠久的黑人学院和大学的长期合作伙伴关系将确保代表性不足的少数群体参与这项研究计划。 技术摘要过去几年，随着使用两级金刚石微砧实现近兆帕斯卡（1 TPa = 1000 GPa）静压以及毫秒 X 射线的发展，极端条件下的过渡金属研究取得了快速进展在同步加速器设施中使用快速探测器的衍射技术。阿拉巴马大学伯明翰分校开发了一种利用化学气相沉积技术制造两级金刚石微砧的新方法。此外，可以使用压电驱动器（动态金刚石砧单元）和掺硼加热砧将快速压力和温度变化应用于样品，从而为研究极端条件下过渡金属和合金的相变和相变动力学提供理想的工具。在这项研究中，重点是钛钒 (Ti) 中六方密堆积（hcp 相）到简单六方（omega 相）转变以及从 omega 相到体心立方（bcc 相）的转变动力学。 -V) 和铪钽 (Hf-Ta) 合金。目标是确定早期过渡金属和合金在静水（氖压力介质）和非静水（无压力介质）条件下是否存在其他新相，例如斜方相变体（γ、δ 和 eta 相）。在锇 (Os) 金属中，在环境温度下 150 GPa 和 440 GPa 下观察到结构异常，值得在高温下进行进一步研究。预计当 s 电子能级在极端压力下移动到费米能级以上时，过渡金属系列的大多数早期成员都会转化为几乎纯的 d 带金属。这项研究将为过渡金属和合金在极端条件下的这种独特电子态提供晶体结构数据和压力体积数据，以便与理论模型直接比较。

项目成果

Ultrahigh pressure equation of state of tantalum to 310 GPa

钽超高压状态方程至310GPa

• DOI: 10.1080/08957959.2019.1641203
• 发表时间: 2019
• 期刊: High Pressure Research
• 影响因子: 2
• 作者: Burrage, Kaleb C.;Perreault, Christopher S.;Moss, Eric K.;Pigott, Jeffrey S.;Sturtevant, Blake T.;Smith, Jesse S.;Velisavljevic, Nenad;Vohra, Yogesh K.
• 通讯作者: Vohra, Yogesh K.

Nanocrystalline diamond micro-anvil grown on single crystal diamond as a generator of ultra-high pressures

• DOI: 10.1063/1.4964299
• 发表时间: 2016-09-01
• 期刊: AIP ADVANCES
• 影响因子: 1.6
• 作者: Samudrala, Gopi K.;Moore, Samuel L.;Vohra, Yogesh K.
• 通讯作者: Vohra, Yogesh K.

High Pressure Structural Parameters and Equation of State of Osmium to 207 GPa

207 GPa 的高压结构参数和锇态方程

• DOI: 10.1080/23311940.2017.1376899
• 发表时间: 2017
• 期刊: Cogent Physics
• 作者: Perreault, Christopher S.;Velisavljevic, Nenad;Vohra, Yogesh K.;Rajeev, Ahuja
• 通讯作者: Rajeev, Ahuja