TiAl-B合金片状TiB<sub>2</sub>晶体表面结构及生长机理

TiAl-B合金片状TiB₂晶体表面结构及生长机理

基金项目: 金属精密热加工国防科技重点实验室开放基金资助项目(99JS61.5.1.ZS6102)

详细信息

1.
School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China;
2.
School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

摘要

摘要: 用原位自生法制备了Ti-54Al-xB (at%)合金并利用XRD,SEM对合金的相组成和微观组织进行了研究。结果表明:片状TiB₂基面存在与[0001]晶向平行的细棒状分枝,表面存在与[0001]晶向垂直的薄片凸耳状分枝,它们的晶体学取向与母体的取向一致。片状TiB₂厚度一般小于0.3μm,表面上的凸耳状分枝厚度一般小于0.1 μm。分析表明,在不平衡凝固条件下,片状TiB₂固-液界面前沿产生的富Al边界层和随着片状TiB₂晶体的长大导致固-液界面上B原子过饱和度不均匀性增加的共同作用使固-液界面失稳,从而形成了片状TiB₂的这种表面结构。
- TiAl /
- TiB₂ /
- 表面结构 /
- 生长机理
Abstract: Ti-54Al-xB alloys have been produced by an in-situ method. The microstructure and phases constituent of these alloys were investigated by XRD and SEM. The results show that there are needle shape dendrites which are parallel to [0001] on the edge of TiB₂ plate and convex flakes which are perpendicular to [0001]on the surface of TiB₂ plate. These needles or flakes exhibit facets parallel to those of TiB₂ plate. It was analyzed that the Al rich layer and inhomogeneity in supersaturation at the solid-liquid interface resulting from non-equilibrium solidification may make the solid-liquid interface unstable, and lead TiB₂ plate to forming the surface structure.
- TiAl /
- TiB₂ /
- surface structure /
- growth mechanism