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.

摘要元素周期表中的一些元素在外部高压和高温作用下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，这些具有增强物理和机械性能的新型晶体改性可以在去除压力后保留，从而具有潜在的工业应用。利用高压和高温将石墨碳转化为金刚石就是这方面研究的一个很好的例子。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创新设计的高压装置中的金刚石砧来产生高达1000万大气压的超高压而实现的。高压技术的进步加上非常明亮的x射线源使我们能够探测晶体结构的变化，因此我们可以在高压和高温下构建各种晶体结构的稳定性图。这些稳定性图将允许研究人员设计新的策略来合成这些材料的批量工业应用。项目参与者将在采用x射线同步辐射进行材料研究的主要国家设施中接受广泛的研究培训，从而在高压科学方面培养训练有素的科学工作人员。我们与东南地区的传统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：随着同步加速器上使用快速探测器的毫秒x射线衍射技术的发展，在极端条件下过渡金属的研究在过去几年中取得了迅速的进展，使用两级金刚石微顶达到了近特帕斯卡（1 TPa = 1000 GPa）的静压。在伯明翰的阿拉巴马大学，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已经被开发出来。此外，使用压电驱动器（动态金刚石砧细胞）和掺硼加热砧可以应用于样品的快速压力和温度变化，从而为研究极端条件下过渡金属和合金的相变和转变动力学提供了理想的工具。在本研究中，重点研究了钛钒（Ti-V）和铪钽（Hf-Ta）合金中六方密堆积（hcp-phase）到简单六方（omega-phase）的转变动力学，以及从omega-phase到体心立方（bcc-phase）的转变动力学。目标是确定在流体静力（氖气压力介质）和非流体静力（无压力介质）条件下早期过渡金属和合金中出现的其他新相，如正交改性（γ， δ和eta相）。在Osmium （Os）金属中，在环境温度下，在150 GPa和440 GPa处观察到结构异常，需要在高温下进一步研究。可以预见，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转化为几乎纯的d带金属。本研究将提供极端条件下过渡金属和合金这种独特电子态的晶体结构数据和压力-体积数据，与理论模型进行直接比较。

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.

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

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.