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

本研究结合钛铝基金属间合金反应动力学的实验测量和详细的定量透射电子显微镜来研究大量相变。在相变过程中发生的原子构型的变化进行了检查，并探讨了相关的动力学，热力学和晶体学特征。结合计算机接口控制和高速数据采集的新型实验技术提供了K和电阻率的原位测量。可控气淬允许冷却速率的变化。将实验测量结果与定量热力学模型相结合，建立界面迁移机理。基于钛铝合金体系的新型合金由于其独特的组合性能，在高温航空航天系统中的应用具有重要意义。这些合金的设计取决于对控制力学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.