微结构对过渡金属钽高压熔化曲线影响机制的理论研究

项目名称： 微结构对过渡金属钽高压熔化曲线影响机制的理论研究

项目编号： No.11504280

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 刘春梅

作者单位： 武汉科技大学

项目金额： 20万元

中文摘要： 金属钽不仅是凝聚态物理研究中的标准材料，更是重要的军事应用材料，但早期研究发现其动高压和静高压实验得到的熔化曲线间存在着无法解释的巨大差异。如何解释这种差异，如何得到一条更加合理的高压熔化曲线一直是高压科学科研中的一个重点也是难点。本项目拟采用从头算分子动力学模拟方法，对比分析静态压缩和动态压缩下样品熔化过程中各种微结构（如空位、位错、晶界等）的产生、演变过程和竞争机制，探索这两种高温高压技术其作用机制的差异，进而在初始模拟样品中预置这些不同的微结构，探索缺陷处的预熔化现象和缺陷的动力学行为，分析各种缺陷对熔化曲线的影响机制，得到包含这些不同微结构的钽的高压熔化曲线，揭示其动高压和静高压熔化曲线巨大差异的原因，为深入研究其他过渡金属的高压熔化曲线奠定基础。

中文关键词： 钽；熔化曲线；微结构；高压；从头算分子动力学模拟

英文摘要： Tantalum (Ta) metal is not only a pressure calibration material in condensed matter physics, but also an important material in military applications. Early reports showed that, great inconsistencies exist in melting curves between the shock wave (SW) and diamond anvil cell (DAC) experiments. How to explain such inconsistencies, and obtain a more reasonable melting curve are always important and difficult questions in high pressure research. In this item, we are aim to apply ab-initio molecular dynamics simulations, including both static and shock compressions to compare the producing, evolvement process, competing mechanism of different microstructures (such as vacancies, dislocations, grain boundaries and so on) in the sample during melting. Thus we can explore the different mechanism of the two high pressure and high temperature techniques. By presetting these microstructures into the initial samples, we further explore the premelting phenomenon at the defects as well as the dynamic behaviors of these defects, analyze their influence mechanism to the melting curve, and obtain the high pressure melting curves of Ta with microstructures. This project not only reveals the reasons for the inconsistencies in melting curves of Ta between the SW and DAC experiments, but also establishes foundations for further investigating the high-pressure melting curve of other transition metals.

英文关键词： Tantalum;Melting curve;Microstructure;High pressure;Ab-initio molecular dynamics simulations