Ta掺杂对γ-TiAl基合金块状组织和力学性能的影响

Influence of Ta Doping on Microstructure and Mechanical Properties of γ-TiAl Based Alloy

  • 摘要: 研究了Ti-48Al-2Nb-2Cr-xTa(x=0,1.0,2.0)(原子分数,%)合金α单相区淬火,块状组织(γm相)的演变规律,采用EBSD(电子背散射衍射)技术对晶粒取向进行表征。结果表明,在快速冷却条件下,微量Ta元素的添加能够促进γm相的析出,促进(体积分数大于50%)或者抑制(体积分数小于50%)γm相析出的Ta元素临界含量为2 %(原子分数)。Ta元素能够细化γm相亚颗粒,同时,不同种类γm变体可直接在α2晶粒内以BOR形核,在生长过程中发生了沿着111γ密排面的变体选择,使得第二代γm变体偏离BOR。

     

    Abstract: The evolution behavior of massive γ (γm) quenching from single α-phase region in Ti-48Al-2Nb-2Cr-xTa (x=0, 1.0, 2.0) alloy is systematically studied. The electron back scattering diffraction method is used to character the grain orientation. The precipitation of γm phase can be greatly promoted by Ta element. The critical content of Ta, promoting or inhibiting the precipitation of γm, is 2% (atom fraction). Ta element can refine the γm subgrains, and the various γm variants can directly nucleate inside the α2 grains in the form of BOR. In the course of growth, the γm nuclei selects its variant over the close-packed 111γ plane, making the γm nuclei deviating from BOR.

     

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