Melting Kinetics of Faceted and Non-Faceted Crystals

刻面和非刻面晶体的熔化动力学

• 批准号: 0314317
• 负责人: Reza Abbaschian
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0314317&HistoricalAwards=false
• 关键词: Melting; Kinetics; Faceted; Non; Crystals

Melting is among the most common physical phenomena known to mankind, yet it has been the most difficult to understand. This grant is aimed at a greater understanding of melting behavior of metals and alloys. The research will provide accurate data on the solid-liquid interface kinetics as a function of the interface superheating, melting rate, and composition. The interface superheating will be measured directly from the Seebeck potential difference generated across two solid-liquid interfaces; one stationary and the other melting at a given velocity. An important feature of the measurement technique is that it allows for a precise, non-intrusive and continuous monitoring of the interface temperature. The materials selected for the study will consist of single crystals of pure Sn (a non-facet forming metal) and Bi (a facet former), and Sn-Bi single crystals containing up to 4 at % Bi. The primary objective of the research is to obtain quantitative information on the interfacial kinetics as a function of melting velocity for single crystals, and on the solute redistribution during melting.The scientific significance of the investigation stems from the fact that melting kinetics provide information on the nature of the interface as it responds to deviations from local equilibrium. Such information will delineate whether the melting interface is diffuse, or whether it behaves similar to that during solidification. In addition to its theoretical significance, the melting kinetics laws are of interest for a series of technical problems such as in the formation of equiaxed structures in castings. Formation of such structures strongly depends on the melting and dissolution kinetics of inoculants, intrinsic solid particles, as well as on the local solidification conditions. The project will expose graduate students to fundamental research and measurement techniques in materials science and engineering.

融化是人类已知的最常见的物理现象之一，但也是最难理解的。这笔赠款旨在更好地了解金属和合金的熔化行为。该研究将提供关于固液界面动力学作为界面过热度、熔化速率和成分函数的准确数据。界面过热度将直接通过两个固液界面产生的塞贝克电势差来测量；一个静止，另一个以给定速度熔化。该测量技术的一个重要特点是它可以对界面温度进行精确、非侵入式和连续的监测。研究中选择的材料将包括纯锡（一种非晶面形成金属）和铋（一种晶面形成物）单晶，以及含有高达 4 at% Bi 的 Sn-Bi 单晶。该研究的主要目的是获得有关单晶熔化速度函数的界面动力学以及熔化过程中溶质重新分布的定量信息。这项研究的科学意义源于这样一个事实：熔化动力学提供了有关界面性质的信息，因为它对局部平衡的偏差做出了响应。这些信息将描述熔化界面是否是扩散的，或者它的行为是否与凝固过程中的相似。除了其理论意义外，熔化动力学定律对于一系列技术问题也很有意义，例如铸件中等轴结构的形成。这种结构的形成很大程度上取决于孕育剂、固有固体颗粒的熔化和溶解动力学以及局部凝固条件。该项目将使研究生接触材料科学与工程的基础研究和测量技术。