Thermodynamic Modeling of Aluminum and Nickel Ternary Alloy Systems

本研究的目的是建立三元铝镍基合金中各相自由能随组成和温度变化的热力学描述。生成热是使用定制的高温反应量热计确定的，典型精度为+/- 1kJ/mol。此外，差热分析将用于确定熔点和其他相变，差热扫描量热法将用于确定选定合金的热容量作为温度的函数。DTA和DSC实验将在新的SETARAM 1750 C量热计中进行。从实验中确定的数据将用于开发一个改进的、自一致的铝镍基合金热力学数据库，该数据库可用于需要高温结构合金的技术。关于铝基和镍基合金体系的此类数据很少或根本不存在。实验结果将用于计算特定成分在给定温度下的最小自由能。这种相图的热力学建模提供了一个机会，以更有效的方式接近合金发展的相平衡方面。改进后的数据库将用于使用THERMOCALC计算每个三元合金系统的几个等温截面。该数据还将用于验证文献中的各种外推模型，用于从二进制数据预测三元化合物的生成热。这项工作在多组分镍和铝基合金的设计中得到了应用，这些合金在许多技术中用作结构材料。该研究的实验结果将为使用CALPHAD方法计算相图提供所需的数据，这种方法比目前可用的技术效率高得多。这些实验数据是不可用的，这将是美国唯一拥有专业知识来满足需求的设施。从基本的角度来看，该项目将推进一个很大程度上未知的研究领域，即涉及多组分、多相、不同阶段的系统。这些系统在许多需要高温结构材料的技术中得到了应用。

The objective of this research is to develop a thermodynamic description for the free energy of each phase as a function of composition and temperature in ternary aluminum and nickel base alloys. The heats of formation are determined using a custom built high temperature reaction calorimeter with a typical accuracy of +/- 1kJ/mole. In addition, differential thermal analysis will be used to determine melting points and other phase transitions and differential scanning calorimetry will be used to determine heat capacity of selected alloys as a function of temperature. The DTA and DSC experiments will be performed in a new SETARAM 1750 C calorimeter. The data determined from the experiments will be used to develop an improved, self-consistent thermodynamic database for Aluminum-Nickel-base alloys that find application in technologies requiring high temperature structural alloys. Such data on Al and Ni-base alloy systems are scarce or non-existent. The experimental results will be used to compute the minimum in free energy for a particular composition at a given temperature. Such thermodynamic modeling of phase diagrams provides an opportunity to approach the phase equilibria aspects of alloy development in a more efficient manner. The improved database will be used to compute several isothermal sections in each of the ternary alloy systems using THERMOCALC. The data will also be used to validate various extrapolation models from the literature for the prediction of heats of formation of ternary compounds from binary data. The work finds application in the design of multi-component nickel and aluminum based alloys that are used in many technologies as structural materials. The experimental results of the study will provide the needed data for phase diagram calculations using CALPHAD methodology that is far more efficient than the currently available techniques. These experimental data are not available and this will be the only facility in USA that has the expertise to fill the need. From a fundamental viewpoint, the project will advance a largely uncharted area of research that is concerned with multi-component, multi-phase systems with varied phases. These systems find application in many technologies that require high temperature structural materials.