Microstructural Design of Two Phase Titanium Aluminides for High Temperature Applications

高温应用两相钛铝化物的微观结构设计

基本信息

批准号：
08455313
负责人：
MARUYAMA Kouichi
金额：
$ 4.93万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455313/
关键词：
High Temperature Structural Materials High Temperature Creep Titanium Aluminides Alloy Design Microstructural Control Lamellar Microstructure Materials Database データベース

项目摘要

TiAl alloys consists of gammaTiAl and alpha_2Ti_3Al phases, and are considered to be a candidate for high temperature structural applications. A further improvement of their high temperature mechanical properties is required for their engineering applications, For the improvement, it is important to know how to optimize their microstructure. In this research, the correlation between the microstructures and high temperature mechanical properties were studied, and the following results were obtained.1. Creep strength of TiAl alloys is independent of grain size for grain sizes greater then 100mum. In the grain size range smaller than 100mum, their creep strength may decrease with decreasing grain size.2. Creep strength of TiAl alloys is insensitive to the volume fraction of constituent phases, in other words, aluminum concentration.3. Creep strength of fully lamellar TiAl alloys is improved by the refinement of their lamellar spacing. At low stresses, however, the high creep strength of f … More ine lamellar microstructure disappears due to the significant degradation of the fine lamellar microstructure. Dynamic recrystallization and discontinuous coarsening of lamellar microstructure during creep are responsible for the degradation, and the consequent weakening of the fine lamellar microstructure.4. The lamellar microstructure can be stabilized by annealing at a high temperature. The stabilization treatment prevent the microstructural degradation during creep, and the strengthening by lamellar refinement becomes effective even at low stresses.5. Creep strength of PST crystals, having only one lamellar colony, depends strongly on the angle between the stress axis and the lamellar plates. The hard oriented crystal, whose lamellar plates are aligned parallel or perpendicular to the stress axis, provides substantially higher creep strength than randomly oriented polycrystalline TiAl alloys. The soft oriented crystal, having an intermediate angle of stress axis to the lamellar plates, shows similar creep strength to the polycrystals. This result suggests that creep strength of polycrystalline TiAl alloys can be improved by the control of their texture. Less

TIAL合金由γ_2TI_3AL相组成，被认为是高温结构应用的候选者。其工程应用需要进一步改善其高温机械性能，为了改进，重要的是要知道如何优化其微观结构。在这项研究中，微观结构与高温机械性能之间的相关性进行了研究，并获得了以下结果。1。 Tial合金的蠕变强度与晶粒尺寸无关，而粒度大于100M。在小于100M的晶粒尺寸范围内，它们的蠕变强度可能随着晶粒尺寸的降低而降低。2。 TIAL合金的蠕变强度对组成相的体积分数敏感，换句话说，铝浓度3。通过层状间距的完善，完全层状tial合金的蠕变强度得到了提高。然而，在低应力下，由于细层状微结构的显着降解，层状微结构中F的高蠕变强度会消失。蠕变过程中层状微结构的动态再结晶和不连续的重结晶是降解的原因，随之而来的是细层状微观结构的削弱。4。可以通过在高温下退火来稳定层状微结构。稳定治疗可防止蠕变过程中的微结构降解，即使在低应力下，层状细化的加强也有效。5。 PST晶体的蠕变强度仅具有一个层状菌落，很大程度上取决于应力轴和层状板之间的角度。与随机定向的多晶型合金相比，硬层晶体的层状板平行或垂直于应力轴平行或垂直于应力轴，而其呈平行或垂直于应力轴。柔软的定向晶体与层状板具有中间的应力轴角，可以通过控制其纹理的控制来改善与多晶型合金相似的蠕变强度。较少的