中文摘要：

γ-TiAl合金是应用前景广泛的轻质高温结构材料，其全片层组织性能具有明显的各向异性。籽晶法定向凝固利用具有特定片层取向的籽晶材料使高温a相沿〈1120〉方向生长，获得与生长方向平行的定向全片层组织：改变凝固路径法则通过在凝固组织中获得全口相生长，使最终片层组织与生长方向呈0°和45°夹角。本文综述了两种方法控制TiAl合金片层取向的原理及其研究进展，讨论了合金成分、凝固参数对片层取向控制过程的影响。针对国内外γ-TiAl合金定向全片层组织制备的现状，提出了需要进一步研究的问题。

英文摘要：

Gamma titanium aluminide （γ-TiAl） alloys are candidate materials for lightweight high-temperature structural applications and the mechanical properties of the alloys with fully lamellar microstructure are extremely anisotropic. In the seed method of directional solidification, the seed crystal materials with special lamellar orientation are applied, the high-temperature a phases are controlled to grow along 〈112 0〉 direction, and finally the fully lamellar microstructures parallel to the growth direction are obtained. Another approach of controlling the orientation of lamellar microstructure is to change the solidification pathway so that the alloys solidify completely with β phases, and the obtained lamellar microstructure is aligned at 0°and 45° angles to the grow direction. This paper summarized the mechanism and recent research progress of the lamellar orientation control by the two methods in TiAl alloys, and systemically studied the effects of the alloy composition and processing parameters on the lamellar orientation control process. Finally the problems of aligned lamellar microstructure preparation in TiAl alloys at home and abroad that needed to be further investigated were presented.