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.

元素周期表中的非技术抽象性元素受到外部高压和高温度的影响，适应了新型的结构修饰，从而改善了其物理和机械性能。在某些情况下，这些新颖的晶体修饰具有增强的物理和机械性能，在去除压力后可以保留，从而导致潜在的工业应用。通过应用高压和高温度，将石墨碳转化为钻石是这项研究的一个典型例子。该研究计划将对在航空航天，生物医学和核工业中广泛使用的过渡金属和合金进行高压高温研究。这项研究是通过在高压装置中使用钻石砧的创新设计在实验室中产生高达一千万个气氛的超高压的进步来实现这项研究的。高压技术的进展以及非常明亮的X射线源使我们能够探测晶体结构的变化，因此我们可以在高高的压力和温度下为各种晶体结构构建稳定图。这些稳定地图将使研究人员能够设计新的策略，以批量形式合成这些材料以用于工业应用。该项目参与者将在材料研究中采用X射线同步辐射的主要国家设施进行广泛的研究培训，从而导致高压科学中训练有素的科学劳动力。我们与东南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该研究计划。 技术摘要在极端条件下对过渡金属的研究在过去几年中取得了迅速的进步，随着近terapascal（1 TPA = 1000 GPA）的静态压力，使用两阶段的钻石微型分子，以及使用X射线射线衍射技术的开发，以及在同步器设施的快速检测器的开发。在伯明翰阿拉巴马大学，已经开发了一种使用化学蒸气沉积技术制造两阶段钻石微型分子的新方法。此外，可以使用压电驱动器（动态钻石砧细胞）和硼掺杂的加热铁砧应用快速压力和温度变化，从而为在极端条件下的过渡金属和合金中提供了理想的工具来研究相变和转化动力学。在这项研究中，重点是将六角形封闭式（HCP阶段）转化为简单的六边形（Omega-phase）转换，以及从钛合金（ti-v）和hafnium-tantantalum（hafnium-tantantalum（hfnium-tantanalum）（hfnium-tantanalum（hf-tanta）中，从欧米茄（Omega-phase）到身体为中心的立方体（BCC-phase）。目的是在早期的过渡金属和静液压金属（NEON压力培养基）和非溶剂抑制（无压力培养基）条件下，建立其他新型阶段的发生，例如在早期过渡金属和合金中的正晶修饰（伽马，三角洲和ETA阶段）。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，需要在升高温度下进一步研究。预计过渡金属系列的大多数早期成员都会转换为几乎纯的D波段金属，因为在极端压力下，S-电子水平在Fermi-Level上方移动。这项研究将在极端条件下为这种独特的过渡金属和合金的电子状态提供晶体结构数据和压力量数据，以直接与理论模型进行比较。

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