Recovery, recrystallization and phase transformations during thermomechanical processing and treatment of TiAl-based alloys
Recovery, recrystallization and phase transformations during thermomechanical processing and treatment of TiAl-based alloys
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DOI：
10.1016/s1359-6454(00)00093-8
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发表时间：
2000-06
期刊：
影响因子：
9.4
通讯作者：
W.J. Zhang;U. Lorenz;F. Appel
中科院分区：
文献类型：
--
作者：
W.J. Zhang;U. Lorenz;F. Appel
Ti-45 Al-10 Nb（at.%）合金铸造组织的转变使用扫描和透射电子显微镜研究了由于挤压和随后的热处理而产生的锭。挤压后，原始片层组织被动态再结晶破坏，形成细晶双相组织，但仍保留有少量残余片层。研究发现，不同地区的残留薄层中的精细亚结构各不相同。再结晶和相界膨胀被认为是负责片层球化的主要机制。残余片层的存在归因于起始片层团的各向异性流动行为。微观结构和工艺变量的影响规模的残余laminates将得到阐明。在（α+γ）两相场中退火不能消除残余片层组织。然而，如果残余薄片小于约80μm，则α处理后残余薄片的有害影响可以最小化。
The conversion of the cast microstructure of a Ti–45Al–10Nb (at.%) ingot due to extrusion and subsequent heat treatments was investigated using scanning and transmission electron microscopy. The starting lamellar microstructure was broken down by dynamic recrystallization into a fine-grained duplex microstructure after extrusion, however, a small amount of remnant lamellae was retained. It was found that the fine substructures in the remnant lamellae varied from one area to another. Recrystallization and phase boundary bulging were found to be the major mechanisms responsible for lamellar globularization. The existence of remnant lamellae was ascribed to the anisotropic flow behavior of the starting lamellar colonies. Microstructural and process variables that influence the scale of remnant lamellae will be elucidated. Annealing in the (α+γ) two-phase field cannot eliminate the remnant lamellar structures. However, the detrimental effect of remnant lamellae can be minimized after alpha treatments provided that the remnant lamellae are smaller than about 80μm.