Bo Chen Yingche Ma Ming Gao Kui Liu
材料科学技术（英）
Experimental studies on the melting process of titanium aluminum alloy have been pursued from the viewpoint of contamination. TiAl alloys were prepared with vacuum induction melting (VIM) in calcia crucibles at 1873 K and 1923 K in order to determine the behavior of the oxygen content as a function of temperature, time and frequency of power. The experiment results showed that alloys were uncontaminated except for the increasing of oxygen content which was introduced from the reaction CaO(s)=Ca(in TiAl)+O(in TiAl), and the standard Gibbs energy of the reaction was determined to be ?G0=274000−102.8T (J/mol). Oxygen content increased slowly with the melting time by about 50×10-6 wt pct/min, and decreased with induction melting frequency. Lower superheat and higher melting frequency can be used to reduce oxygen content increasing rate.
关键词:
TiAl alloys
,
induction melting
,
calcia crucible
,
oxygen content.
H.F. Wang
,
J.J. Guo
,
G.F. Mi
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
金属学报(英文版)
Solute diffusion controlled solidification model was applied to simulate the columnar to equiaxed transition (CET) during directional solidification of of TiAl alloys. The simulation results showed that the solutal interactions from growing equiaxed grains play an important role on CET, which can render a large fraction of seeds inactive. The effects of the applied temperature gradient and pulling speed, the equiaxed seed spacing and nucleation undercooling on the CET are investigated in present simulation. It indicated that the columnar branch spacing depends not only on the temperature gradient and the pulling speed, but also number of the seeds, a spacing adjustment can occur through initiation of seeds that develop into new columnar grains. The dependence of the CET on the temperature gradient and pulling speed, qualitatively agrees with the analytical CET model of Hunt.
关键词:
TiAl alloys
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null
,
null
J.Zhang
,
K.Xia
材料科学技术（英）
Enhancing mechanical properties and improving reliability of TiAl alloys by utilizing the mechanical anisotropy of the cast lamellar structure were reported. A self-oriented lamellar (SOL) microstructure was successfully produced in shaped components. After modification by hot isostatic pressing, such a microstructure exhibited improved mechanical properties. The TiAl rotor blades with SOL in a turbocharger passed rotation rig tests and showed enhanced engine performance.
关键词:
TiAl alloys
,
null
,
null
刘杰
,
薛祥义
,
杨劼人
,
寇宏超
,
李金山
,
胡锐
稀有金属材料与工程
以Ti-48A1-2Cr-2Nb(at％)合金为研究对象,通过热处理获得近片层和全片层两种显微组织,并在800℃空气条件下,进行了100 h的抗氧化性实验.利用OM、SEM、TEM、XRD和EDS对试样的微观结构、相组成及微区成分进行了分析.恒温氧化动力学结果表明:在800℃空气条件下,对于近片层和全片层两种TiAl合金组织,其恒温氧化动力学曲线符合近抛物线规律,且近片层组织合金的抗氧化性能优于全片层组织.基于氧化动力学曲线、组织结构、氧化膜结构、氧化表面形貌分析,表明TiAl合金的片层组织结构对其氧化行为具有不可忽视的影响.
关键词:
TiAl合金
,
显微组织
,
片层结构
,
氧化行为
刘杰
,
薛祥义
,
杨劼人
稀有金属材料与工程
以Ti-42Al-8Nb-0.2W-0.1Y(at％)合金为研究对象,通过热处理获得全片层组织,片层团尺寸约为85 μm,在900℃空气条件下,对合金进行了100 h的抗氧化实验,主要研究了该TiAl-Nb合金的高温抗氧化行为,并对氧化层的结构、成分及形成过程进行了深入分析.利用OM、SEM、XPS、XRD、和EDS对试样的微观结构、相组成及微区成分进行表征.结果表明:在900℃空气条件下,具有全片层组织的TiAl-Nb合金,其恒温氧化动力学曲线符合近抛物线规律;长时氧化后,合金表面生成了结晶状颗粒氧化物,为TiO2和Al2O3的混合物;氧化层主要由外表面氧化层、中间过渡层和基体层构成,氧化膜完整厚度大约为6μm.由此可知,添加了合金元素且具有小尺寸片层团组织的TiAl合金在900℃高温时,具有较好的抗氧化性能.
关键词:
TiAl合金
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显微组织
,
片层结构
,
氧化行为
贺进
,
周汉
,
朱文琪
,
鲁雄刚
,
李重河
材料导报
doi:10.11896/j.issn.1005-023X.2014.15.017
TiAl金属间化合物具有低密度、高弹性模量、高比强度、良好的抗高温蠕变和抗高温氧化性能,被认为是极具潜力的高温结构材料,在航空航天及汽车发动机领域具有广阔的应用前景,特别是经定向凝固得到的TiAl合金在综合力学性能方面可得到良好的配合.然而,TiAl合金熔体由于具有高的化学活性,会与所有已知的耐火材料发生不同程度的化学反应,限制了其定向凝固铸件的生产和应用.首先回顾了TiAl合金的熔炼技术,然后对TiAl合金精密铸造及定向凝固用耐火材料的研究现状进行了总结,在此基础上提出了一种新型的TiAl合金定向凝固用BaZrO3耐火材料,并展望了其今后的发展.
关键词:
TiAl合金
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定向凝固
,
耐火材料
,
BaZrO3
陈玉勇
,
孔凡涛
,
崔宁
中国材料进展
doi:10.7502/j.issn.1674-3962.2015.05.09
TiAl金属间化合物板材以其低密度、高强度、高刚度和优异的抗蠕变和抗氧化性能等优点,在航空航天领域,成为替代700～900℃使用的高温合金板材的重要高温结构材料.目前,TiAl金属间化合物板材的制备方法主要为铸锭冶金技术(IM)和粉末冶金技术(PM).本文采用铸锭冶金技术(近等温包套轧制技术)成功制备了尺寸为700 mm×200 mm×2 mm的TiAl合金板材.TiAl合金板材外观完整,无宏观及微观裂纹等缺陷.TiAl合金板材显微组织为近双态组织,由γ相、B2相和少量的α2相、YAl2相组成.其中B2相含量达到24％,呈块状或片状分布在γ相基体中,B2相高温下转变为无序β相可显著改善合金的高温变形能力.TiAl合金板材显微组织中存在较多的块状γ相和B2相,这主要是由于高温轧制过程中的动态再结晶和静态再结晶引起的.
关键词:
TiAl合金
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铸锭冶金
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热轧
,
板材
,
组织
,
再结晶
