A Study of Massive and Other Phase Transformations in Tial-Bases Intermetallic Alloys

本研究将钛铝化物基金属间化合物合金的反应动力学实验测量与详细的定量电子显微镜相结合，以研究大量的相变。研究了在相变过程中原子构型的变化，并探索了相关的动力学、热力学和结晶学特征。新的实验技术结合了用于控制和高速数据采集的计算机接口，提供了K和电阻率的现场测量。受控气体淬火允许冷却速度的变化。实验测量结果被纳入定量热力学模型，以建立界面迁移机制。基于钛铝化物合金系的新型合金以其独特的性能组合在高温航空航天系统中具有重要的应用价值。这些合金的设计取决于对控制机械性能的相变和相平衡的理解。

This research combines experimental measurements of reaction kinetics in titanium aluminide-based intermetallic alloys with detailed quantitative transmission electron microscopy to study massive phase transformations. Changes in atomic configuration occurring during phase transformation are examined and the associated kinetic, thermodynamic, and crystallographic features are explored. Novel experimental techniques incorporating a computer interfaced for control and high speed data acquisition provide in situ measurements of K and electrical resistivity. Controlled gas quenching permits variation in cooling rate. The experimental measurements are incorporated in quantitative thermodynamic models to establish mechanisms of interface migration. %%% New alloys based on the titanium aluminide alloy system are of great importance for applications in high temperature aerospace systems because of their unique combinations of properties. Design of these alloys depends on understanding the phase transformations and phase equilibria that control mechanical properties.