(1. 中国科学院金属研究所，沈阳110016；
2. 长沙中联重工科技发展股份有限公司，长沙 410013；
3. The Ohio State University, Columbus, OH 43210, USA)
摘 要: 采用相场方法模拟Ti-6Al-4V合金β→α相变过程，对共格α析出相变体形貌及其惯习面取向进行研究。模型输入数据源自Thermo-Calc热力学和Dictra动力学数据库，通过构造梯度项系数张量考虑界面能各向异性的影响，基于Khachaturyan微观弹性理论考虑弹性应变能的影响。结果表明：片状α相的形貌及惯习面取向是界面能各向异性及弹性应变能共同作用的结果；变体的生长由溶质原子的扩散所控制，在生长过程中，在相界β侧形成Al原子的贫瘠区与V原子的富集区；界面能越大的方向上片层生长越快；根据Burgers关系，由同一(110)晶面衍生出的两种α变体惯习面取向夹角约为100°，经旋转对称操作可推算出任意两变体间共有5种夹角。
关键字: Ti-6Al-4V合金；相场模拟；弹性应变能；微观组织演化；析出
（1. Institute of Metal Research, Chinese Academy of Science, Shenyang110016, China;
2. Zoomlion Heavy Industry Science and Technology Development Co., Ltd, Changsha 410013, China;
3. The Ohio State University, Columbus, OH 43210, USA）
Abstract:To investigate the morphology and habit plane orientation of α precipitates, the α precipitation process in b→α transformation were simulated by phase field method using the Thermo-Calc thermodynamic and Dictra kinetic databases as direct input of the model. The phase field approach takes into account interface energy anisotropy and elastic strain energy by means of gradient energy tensor and microelasticity theory by Khachaturyan, respectively. The results show that the interface energy anisotropy and elastic strain energy play important roles in determining the morphology and habiting plane orientation of α precipitates. The growth of α precipitates is a diffusion-controlled process. The solute concentrations are found inhomogeneous near α/β interface (Al-poor and V-rich on the β side), and the larger interface energy is, the faster α phase grows. According to Burgers relationship, the angle between the two variants derived from the same β slip plane is 100°. There are five angles between any two variants via symmetry operations.
Key words: Ti-6Al-4V alloy; phase field simulation; elastic strain energy; microstructure evolution; precipitation
