钛铝合金由于密度低且高温下综合力学性能好，在航天航空发动机制造领域具有重要应用。高温高压下的显微组织结构及相关系是决定钛铝合金性能的关键。构建钛铝合金高压相图既能预测合金显微结构也能揭示相变行为，然而极端条件的相图测试难度限制了其发展。本项目拟结合先进原位衍射技术与相图热力学计算，以钛-铝二元系为例开展以下研究：1）利用原位同步辐射/中子衍射系统研究钛-铝二元系高温高压下相平衡及相变关系，通过海量衍射数据的精准拟合建立合金相及有序/无序相的状态方程；2）利用相图热力学计算方法结合高压相图相变测试与关键第一性原理计算，建立完备的钛-铝二元系高压热力学数据库。通过研究揭示钛-铝体系在高压诱导下的固态相变规律及物理现象，建立复杂相结构的高压吉布斯自由能模型。研究成果有望为钛铝合金的高压相图热力学研究打下基础，为其它合金设计提供一种可鉴的研究思路。

Ti-Al alloy has been widely applied in the aerospace engine manufacturing due to its low density and good mechanical properties at high temperature. Microstructure and phase relationship under high-temperature and high-pressure are the key to determine the performance of Ti-Al alloy. Constructing phase diagrams of Ti-Al alloy at high-pressure not only predicts the microstructure but also reveals the phase transition behaviour. However, the difficulties of phase diagram determination under extreme conditions limit its development. Therefore, taking the Ti-Al binary system as an example, this project intends to carry out the following researches by combining advanced in-situ diffraction technology and phase diagram calculation method together: 1) Establishing the phase equilibria and order-disorder transitions in Ti-Al system under high-pressure and high-temperature via in-situ synchrotron radiation and neutron diffraction studies, constructing the equations of state of the compounds and ordered/disordered phases through an accurate fitting to the massive diffraction data. 2) Using the phase diagram calculation method combined with phase diagram & phase transition determinations under high-pressure and the key first-principle calculations to establish a complete thermodynamic database for Ti-Al binary system. The research will reveal the solid-state phase transition behaviour & new physical phenomena in the Ti-Al binary system under high-pressure, and establish a Gibbs energy model to describe the thermodynamic properties of complex phases at high-pressure. The research results are expected to lay the foundation for the thermodynamic research of Ti-Al alloys under high-pressure, and provide a new research approach for other alloy designs.