| 引用本文: | 韩 涛,黄泽文.热处理和热暴露后Ti-46Al-8Ta合金的显微组织和拉伸性能[J].材料科学与工艺,2013,21(2):90-95.DOI:10.11951/j.issn.1005-0299.20130216. |
| HAN Tao,HUANG Ze-wen.Microstructures and tensile properties of Ti-46Al-8Ta after heat treatment and thermal exposure[J].Materials Science and Technology,2013,21(2):90-95.DOI:10.11951/j.issn.1005-0299.20130216. |
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| 摘要: |
| 铸造Ti-46Al-8Ta合金经过专门设计的组合热处理,实现了晶粒细化.对晶粒细化的Ti-46Al-8Ta合金开展了在700℃大气环境中的热暴露5000h的热稳定性评定.采用光学显微镜、扫描电镜、透射电镜、X射线衍射等技术研究晶粒细化工艺以及热暴露对合金组织的影响,并进行了室温拉伸性能测试.研究发现,铸造Ti-46Al-8Ta合金经热等静压和α单相区固溶＋空冷,以及随后的双相区退火能获取晶粒细小的“旋绕态”全片层组织.在700℃长期大气热暴露后,该细化组织发生明显的晶团融合、粗化,并生成出相当数量的B2(ω)和γ新相,导致屈服强度和塑性下降. |
| 关键词: Ta-containing TiAl合金 晶粒细化 热稳定性 相变 拉伸性能 |
| DOI：10.11951/j.issn.1005-0299.20130216 |
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| Microstructures and tensile properties of Ti-46Al-8Ta after heat treatment and thermal exposure |
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HAN Tao,HUANG Ze-wen
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(School of Materials Science and Engineering,Key Laboratory of Advanced Technologies of Materials,Ministry of Education,Southwest Jiaotong University,Chengdu 610031China)
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| Abstract: |
| The grains of cast Ti-46Al-8Ta alloy were refined by a specifically designed heat treatment scheme,and the alloy was thermally exposed at 700℃ in air for up to 5000h to assess the stability of the refined microstructure and mechanical properties.The changes in microstructure and phase structure were characterized using optical microscope,scanning electron microscopy,transmission electron microscopy and X-ray diffraction.The corresponding changes in mechanical properties were examined by tensile testing at room temperature.It was found that after hot isostatic pressing,solid solution in a single α phase region,air cooling and annealing in an α+γ two-phase region,the Ti-46Al-8Ta alloy had shown a grain refined convoluted fully lamellar microstructure.It was important to find that the refined grain structure was thermodynamically unstable.The refined grains structure was eventually coarsened after a long-term exposure at 700℃ during which great deal of B2(ω) phase and equiaxed γ formed by consuming the convoluted lamellar colonies,leading to a reduction both in strength and in ductility. |
| Key words: Ta-containing TiAl alloy Grain refinement Thermal stability Phase transformations Tensile properties |
