New Rules for Coupled Severe Plastic Deformations, Phase Transformations, and Structural Changes in Metals under High Pressure

高压下金属耦合严重塑性变形、相变和结构变化的新规则

基本信息

批准号：
2246991
负责人：
Valery Levitas
金额：
$ 60万
依托单位：
Iowa State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2023
资助国家：
美国
起止时间：
2023-06-01 至 2026-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2246991&HistoricalAwards=false
关键词：
New Rules Coupled Severe Plastic

项目摘要

NON-TECHNICAL ABSTRACTProcesses that require extreme stretching, bending and forming of metals into useful parts typically involve using very high pressures to do so. These very high-pressure methods are used widely to create materials with very specific properties on the inside and at their surface. However, all these operations are generally studied after the events have been completed. This award supports a fundamental quantitative study of these processes while they are occurring and is focused on finding new laws that relate the severe stretching of metal, their evolution at a very fine scale, on the order of a human hair, and the accompanying changes in the metal, called phase transformations. In this project, Titanium, a mixture of Titanium and Zirconium, and an alloy of Aluminum-Iron-Cobalt-Nickel-Copper are being studied under high pressures and strain rates typical of current and future materials technologies. In addition, the project provides opportunities to educate and train undergraduate students, graduate students and a postdoc in the areas of materials, high-pressure sciences and materials processing. This is being accomplished through special courses and research at the PI’s institution, experiments at an extremely high-powered x-ray facility called a “synchrotron” and interaction between experimental and computational efforts, all with an emphasis on underrepresented students.TECHNICAL ABSTRACTThe goal of the project is to perform a fundamental in-situ quantitative study and find new laws for coupled severe plastic deformation, nanostructure evolution, and phase transformations in Ti, a mixture of Ti and Zr, and a AlFeCoNiCu high entropy alloy. These metals will be explored over a broad range of straining programs under pressures up to 65 GPa, and strain rates in the range 10-5-103/s. Experiments will be conducted using a dynamic rotational diamond anvil cell and the intellectual merit will be derived from the quantitative checking of our hypotheses, including: (a) Are crystallite size and dislocation density of all phases getting pressure-, strain- and strain-path-independent, steady-state values before and after phase transformations, and does this depend on the volume fractions during phase transformations and/or the strain rate? (b) Does each phase behave like a perfectly plastic, isotropic, and strain-path-independent material for each strain rate and what is the pressure and strain rate dependence of the yield strength? (c) Are phase transformation kinetics independent of strain path? (d) Does a high strain rate promote phase transformations due to increased yield strength? And (e) Will phase transformations in each material in the Ti-Zr mixture be promoted in comparison to single material studies due to additional obstacles for dislocation pileups?Methods to determine the evolution of highly heterogeneous fields of stress, plastic strain, strain rate tensors, volume fraction of phases, crystallite size, dislocation density, and concentration of species in a dynamic rotational diamond anvil cell will be developed, all in real time, using in-situ X-ray diffraction and other diagnostics in a feedback loop. In addition, simulations including a microscale phase field and physics-based macroscale model as well as a finite-element simulation of the experiments are being developed. Parameter identification, machine learning, model refinement, and all material properties (e.g. viscoplastic, evolution of phase transformations, crystallite size, dislocation density) are being determined, and quantitative models are also being finalized. For broader impacts beyond the technical contributions, a graduate course is being developed, and mentoring opportunities in research for undergraduate students, graduate students and a post-doc are being carried out in conjunction with this project.This project is jointly funded by the Metals and Metallic Nanostructures Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要需要对金属进行极端拉伸、弯曲和成型为有用零件的工艺通常涉及使用非常高的压力来实现这些非常高的压力方法被广泛用于制造内部和表面具有非常特定性能的材料。然而，所有这些操作通常都是在事件完成后进行研究，该奖项支持对这些过程发生时的基础研究，重点是寻找与金属的剧烈拉伸及其在非常精细的尺度上的演化相关的新定律。 ,在这个项目中，正在研究钛、钛和锆的混合物以及铝-铁-钴-镍-铜合金。此外，该项目还为材料、高压科学和材料加工领域的本科生、研究生和博士后提供了教育和培训的机会。通过 PI 机构的特殊课程和研究、在称为“同步加速器”的极高功率 X 射线设施中进行的实验以及实验和计算工作之间的互动来完成，所有这些都重点关注代表性不足的学生。技术摘要该项目的目标是进行基本的原位定量研究，并找到 Ti、Ti 和 Zr 的混合物以及 AlFeCoNiCu 高温耦合严重塑性变形、纳米结构演化和相变的新规律这些金属将在高达 65 GPa 的压力和 10-5-103/s 范围内的应变速率下进行各种应变程序的探索，并使用动态旋转金刚石砧池和智能传感器进行实验。优点将来自对我们假设的定量检查，包括：（a）所有相的微晶尺寸和位错密度在相变之前和之后是否获得与压力、应变和应变路径无关的稳态值,这是否取决于相变期间的体积分数和/或应变率？ (b) 对于每个应变率，每个相的行为是否都像完美塑性、各向同性且与应变路径无关的材料以及压力和应变是多少？ (c) 相变动力学与应变路径无关吗？ (d) 高应变率是否会因屈服强度的增加而促进相变？ (e) Ti 中的每种材料是否会发生相变？ Zr混合物相比有提升由于位错堆积的额外障碍而进行的单一材料研究？确定动态旋转金刚石中应力、塑性应变、应变率张量、相体积分数、微晶尺寸、位错密度和物质浓度的高度异质场演化的方法砧室将使用原位 X 射线衍射和反馈回路中的其他诊断技术实时开发。此外，模拟包括微观相场和基于物理的宏观模型以及实验的有限元模拟正在开发中，参数识别、机器学习、模型细化和所有材料特性（例如粘塑性、相变演化、微晶尺寸、位错密度）都正在确定中，定量模型也正在最终确定中。为了实现技术贡献以外的更广泛影响，正在开发研究生课程，并结合该项目为本科生、研究生和博士后提供研究指导机会。该项目由金属和金属学会共同资助金属纳米结构计划和刺激竞争性研究的既定计划 (EPSCoR)。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。