Tensile and High Cycle Fatigue Properties of a Minor Boron-Modified Ti-22Al-11Nb-2Mo-1Fe Alloy
Tensile and High Cycle Fatigue Properties of a Minor Boron-Modified Ti-22Al-11Nb-2Mo-1Fe Alloy
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DOI：
10.2320/matertrans.m2012043
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发表时间：
2012-06-01
影响因子：
1.2
通讯作者：
Emura, S.
中科院分区：
文献类型：
--
作者：
Hagiwara, M.;Kitaura, T.;Emura, S.
Ti3Al （α(2)相）基Ti-22Al-11Nb-2Mo-1Fe （in at%）合金是Ti2AlNb（0相）基正交Ti-22Al-27Nb （in at%）的衍生物，旨在降低Nb含量，从而降低材料成本。在本研究中，采用微量添加硼(B)和（B2 + α(2)）两相区热处理两种显微组织改性方法来细化该合金的显微组织，从而提高其延展性。当添加0.1质量% B时，铸态铸锭的B2晶粒尺寸从600-1000 μ m急剧减小到100-200 μ m，从而获得了精细的全层状组织。热处理后形成由球形α - 2相和片层状组织区组成的双相组织，其细化程度明显高于无b合金。与不含b的合金相比，具有精致的全片层或双相组织的b改性合金具有更高的拉伸延展性、更高的高周疲劳强度和更好的蠕变性能。疲劳裂纹不是由TiB/基体界面引起的，也不是由TiB本身引起的，而是由合金的基体区域引起的。结果表明，少量B的加入对Ti-22Al-11Nb-2Mo-1Fe合金的整体力学性能有良好的影响。(doi: 10.2320 / matertrans.M2012043)
The Ti3Al (alpha(2) phase)-based Ti-22Al-11Nb-2Mo-1Fe (in at%) alloy is a derivative of Ti2AlNb (0 phase)-based orthorhombic Ti-22Al-27Nb (in at%) and was designed to reduce Nb content and thereby material cost. In the present study, two microstructure modification methods, a minor addition of boron (B) and a thermo-mechanical treatment in the (B2 + alpha(2)) two-phase region, were applied to refine the microstructure of this alloy and thus to improve its ductility. The prior B2 grain size of the as-cast ingot was drastically reduced, from 600-1000 to 100-200 mu m with the addition of 0.1 mass% B, and thereby a refined full lamellar microstructure was obtained. The duplex microstructure consisting of spherical alpha 2 phases and lamellar microstructure area was formed by the thermo-mechanical treatment, which was much finer in the B-modified alloy than in the B-free alloy. The B-modified alloy with a refined full lamellar or duplex microstructure showed higher tensile ductility, as well as higher high cycle fatigue strength and superior creep properties compared to those of the B-free counterpart. The fatigue crack initiated neither from the TiB/matrix interface nor from the TiB itself, but rather from the matrix area of the alloy. Thus, it was confirmed that the addition of a small amount of B exerts a favorable effect as a whole on the mechanical properties of the present Ti-22Al-11Nb-2Mo-1Fe alloy. [doi:10.2320/matertrans.M2012043]