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Process Development for the Orientation Control of the(α_2+γ)Lamellar Microstructure in TiAl Intermetallic Compounds

TiAl金属间化合物(α_2+γ)层状微观结构取向控制工艺开发

基本信息

批准号：
09450259
负责人：
FUKUTOMI Hiroshi
金额：
$ 8.77万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 2000
项目状态：
已结题

项目摘要

Two basic processes designed for controlling the orientaion of lamellar microstructure of with the constituents of α_2+γ phases in the TiAl based alloys are theoreticall and experimentally examined. The first process consists of the high-temperature deformation in α single phase region followed by the annealing and deformation in α_2+γ region. The uniaxial compression in the α single phase region resulted in the formation of a fiber texture, though dynamic recrystallization occurred. The maximum pole density for the compression plane appeared about 35 degrees away from(0001)of α_2 phase. The heat treatment generates the lamellar microstructure reflecting the texture formed by the uniaxial deformation in the α single phase region. Work softening was observed at the deformation of the specimen with fully lamellar microstructure formed by the deformation in the α single phase region and the annealing in the two phase region. The deformation in the two phase region brought about the rotation of the lamellae. The lamellar interface lied almost parallel to the compression plane after the deformation of about-0.8 in true strain.The second process is designed on the basis of the reactive diffusion between the textured titanium foils and aluminum foils. Thermal process consists of four heating stages and a cooling stage for lamellar construction. The phases are examined after the heat treatments by EDX.It was found that 40-60% of the orientations of the lamellae are dominated by the texture of the starting titanium foils. It was concluded that the combination of the reactive diffution process and the thermomechanical treatment described above is promising for the manufacturing process of TiAl sheet materials with the oriented lamellar microstructure.

对TiAl基合金中α_2+γ相成分控制层状显微组织取向的两种基本工艺进行了理论和实验检验。第一个过程包括α单相区的高温变形，然后是α_2+γ区的退火和变形。尽管发生动态再结晶，α单相区域的单轴压缩导致纤维织构的形成。压缩面的最大极密度出现在距α_2相的(0001)约35度处。热处理产生反映α单相区单轴变形形成的织构的层状显微组织。在α单相区变形和两相区退火形成的完全层状显微组织的试样变形时观察到加工软化。两相区的变形引起片层的旋转。真应变变形约0.8后，层状界面几乎平行于压缩平面。第二个过程是基于织构化钛箔和铝箔之间的反应扩散而设计的。层状结构的热加工过程由四个加热阶段和一个冷却阶段组成。热处理后通过 EDX 检查相。发现 40-60% 的片晶取向由起始钛箔的织构决定。结论是，上述反应扩散工艺和形变热处理的结合对于具有取向层状微观结构的 TiAl 板材的制造工艺来说是有前景的。