钛铝熔体遗传性影响的定向片层结构及其变形机理研究

项目名称： 钛铝熔体遗传性影响的定向片层结构及其变形机理研究

项目编号： No.51471062

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 丁宏升

作者单位： 哈尔滨工业大学

项目金额： 82万元

中文摘要： TiAl是最佳的下一代轻质耐热结构选材，通过减重促进航空、航天和运输等领域的高效和减排。TiAl的本征脆性可通过具有规则片层取向排列的定向凝固组织来改善。但TiAl属包晶合金体系，复杂的晶体竞争生长规则和多变的凝固路径走向常常导致对定向凝固组织和析出相，如形态、含量和取向的控制变得困难。特别是可工程化的TiAl由于其组分多样，熔炼工艺与中间合金成分的不同，常造成性能的不稳定，尤其是对室温塑性的影响很大。因此，是否可通过对TiAl合金熔体结构与片层组织之间的遗传性研究，找到克服上述困难的方法。本研究项目拟采用液态和电固/固相结合的方法，对TiAl合金熔体结构转变行为及片层组织遗传性进行研究，阐明冷坩埚定向凝固过程中，熔体结构对凝固行为、片层组织取向分布的作用机理，揭示定向凝固TiAl合金片层取向对变形过程的影响机制。为TiAl基合金构件的材料优化、性能提高以及具备工程化应用前景奠定理论基础。

中文关键词： γ-TiAl；定向凝固；冷坩埚；遗传性；变形机理

英文摘要： Due to it exhibits properties of low density, high specific strength, excellent burning and oxidizing resistance at elevated temperature from 700℃ to 900℃, γ-TiAl alloy has been receiving considerable attention as one of the promising structural materials for application in aviation, automotive and power generation industries. However, the intrinsic brittleness of TiAl alloys as an intermetallic compound has seriously restricted its applications. Through controlling the composed γ/α2 lamellar boundaries aligned to the tensile direction by unidirectional solidification technique, the performance of TiAl based alloy can be improve, especially a good combination of room temperature toughness, ductility and high temperature strength. Owing to the peritectic nature of TiAl, the complex rules of competitive crystals growth and the changes in solidification path often lead to difficulties in the control of directional solidification microstructure and precipitation in terms of the shape, content and orientation. Particularly for those engineering TiAl, the diversity in chemical composition, differences in melting process and inter-mediate alloy composition often lead to unstable mechanical behaviour, especially the ductility at room temperature. Therefore, hereditary study on the TiAl alloy melt structure and lamellar structure may lead to the solutions for these problems to be delivered. In the present research, the rapid quenching and resistivity measurements methods were combined to study the structure transformation behaviour of TiAl alloy melt structure and lamellar hereditary. The effects of melt structure on the solidification behaviour, lamellar orientation and deformation mechanism, during the directional solidification process in the cold crucible, have been investigated. The theoretical basis has been developed for the materials optimization of TiAl alloy, performance improvement and the prospect engineering applications.

英文关键词： γ-TiAl;directional solidification;cold crucible;heredity;deformation mechanism