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陈光团队NATURE MATERIALS论文摘要
送交者:  2016年06月24日05:13:21 于 [世界军事论坛] 发送悄悄话
the abstract of the paper the team has published in Journal Nature:

http://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat4677.html

Polysynthetic twinned TiAl single crystals for high-temperature applications
TiAl alloys are lightweight, show decent corrosion resistance and have good mechanical properties at elevated temperatures, making them appealing for high-temperature applications. However, polysynthetic twinned TiAl single crystals fabricated by crystal-seeding methods face substantial challenges, and their service temperatures cannot be raised further. Here we report that Ti–45Al–8Nb single crystals with controlled lamellar orientations can be fabricated by directional solidification without the use of complex seeding methods. Samples with 0° lamellar orientation exhibit an average room temperature tensile ductility of 6.9% and a yield strength of 708 MPa, with a failure strength of 978MPa due to the formation of extensive nanotwins during plastic deformation. At 900°C yield strength remains high at 637MPa, with 8.1% ductility and superior creep resistance. Thus, this TiAl single-crystal alloy could provide expanded opportunities for higher-temperature applications, such as in aeronautics and aerospace.

At a glance
leftright

[IMG]
a, Bright-field TEM image of a tensile specimen showing the original α2/γ lamellar structure before the test. b, After the tensile deformation, the bright-field TEM image reveals the ultrafine twinning and lamellar structure, with the selected area electron diffraction pattern (inset). c, A high-resolution (HR) TEM image of the deformed specimen showing multiple-twinned structures containing three twin boundaries γA/γB, γB/γC and γC/γD.

[IMG]
a, Mechanical properties as a function of temperature. The well-aligned PST single crystal maintains a high yield strength of 637MPa at 900°C; a temperature much higher than the 650–750°C reported for polycrystalline alloys4 (see the pink-colour region in the figure). b,c, The true stress–strain curve and the work hardening rate obtained at ambient temperature (b) and 900°C (c). d, TEM microstructure of well-aligned PST single crystals after tension tested at 900°C. Twins and dislocations appear simultaneously after the elevated-temperature deformation.

[IMG]
a
, Creep strain–lifetime curves. The red lines are for the Ti–45Al–8Nb PST single crystals and the blue lines for the 4822 alloys. The inset is the creep strain–lifetime curves of the 4822 commercial alloy under stresses of 150 and 210MPa. b, Comparison of the minimum creep rates of the single and polycrystalline materials.
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  大家还是要冷静讨论,陈光这么说的 - 老张 06/24/16 (1000)
    因为他发表的测试稳定就是900度。  /无内容 - 古宇庙 06/24/16 (449)
      是那么回事,研究人员的用词其实是非常精准的,  /无内容 - 道友 06/24/16 (507)
        可搞宣传的文科不明白,他们一吹,立刻走样。  /无内容 - 道友 06/24/16 (486)
          不要搞文科理科的优越感行不? - 月落猪蹄 06/24/16 (465)
            猪蹄还没被吃呢?  /无内容 - 道友 06/24/16 (415)
          这个古宇庙也许也就是想套套情报。装出一副义愤填膺的样子而已。  /无内容 - buaa_chc 06/24/16 (447)
            搞不懂这些技术,但是,感觉老道比较专业,知道更多细节。  /无内容 - 月落猪蹄 06/24/16 (445)
  有在技术上不同意陈光的, - Laotu 06/24/16 (784)
    他第一句话就出问题了 - 道友 06/24/16 (799)
      你是决意诋毁。论文明明给了和GE合金的高温实验对比 - 古宇庙 06/24/16 (523)
        那不都是比较的力学性能么?跟你说抗高温能力决定于抗氧化能力  /无内容 - 道友 06/24/16 (430)
          他的研究有突破,但突破在不重要的方面,这就是真相  /无内容 - 道友 06/24/16 (469)
            这不是真相,是你的梦想  /无内容 - 古宇庙 06/24/16 (433)
            为何中国发动机寿命短,就是材料高温抗腐蚀能力没过关  /无内容 - 道友 06/24/16 (431)
              这话再次证明你是个被忽悠了的外行。 - 古宇庙 06/24/16 (506)
              师昌绪那些人就是搞力学性能的,把研发自己都搞去了  /无内容 - 道友 06/24/16 (460)
                材料高温化学腐蚀方面缺乏重视,所以才导致落后三十年  /无内容 - 道友 06/24/16 (425)
      物理性质和化学性质是材料两方面,国内高温合金研究两条腿瘸一条  /无内容 - 道友 06/24/16 (497)
        在高温下决定性的是高温抗氧化能力而不是强度,  /无内容 - 道友 06/24/16 (446)
          你要瘸了最重要那一腿,不落后三十年那才是奇怪。  /无内容 - 道友 06/24/16 (531)
            注意:若有人要跟帖讨论,不要离开高温前提。  /无内容 - 黑木崖 06/24/16 (494)
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