Gong Xuebo, Duan Zhenxin, Pei Wen, Chen Hua
School of Materials Science and Engineering, Changchun University of Technology, Changchun 130012, China.
Materials (Basel). 2017 Sep 19;10(9):1103. doi: 10.3390/ma10091103.
In this paper, the equiaxed superfine/nanocrystalline duplex PM-TiAl-based alloy with (γ + α₂) microstructure, Ti-45Al-5Nb (at %), has been synthesized by high-energy ball milling and vacuum hot pressing sintering. Superplastic deformation behavior has been investigated at 1000 °C and 1050 °C with strain rates from 5 × 10 s to 1 × 10 s. The effects of deformation on the microstructure and mechanical behaviors of high Nb containing TiAl alloy have been characterized and analyzed. The results showed that, the ultimate tensile strength of the alloy was 58.7 MPa at 1000 °C and 10.5 MPa at 1050 °C with a strain rate of 5 × 10 s, while the elongation was 121% and 233%, respectively. The alloy exhibited superplastic elongation at 1000 and 1050 °C with an exponent (m) of 0.48 and 0.45. The main softening mechanism was dynamic recrystallization of γ grains; the dislocation slip and γ/γ interface twinning were responsible for superplastic deformation. The orientation relationship of γ/γ interface twinning obeyed the classical one: (001)//(110).
在本文中，通过高能球磨和真空热压烧结合成了具有（γ + α₂）微观结构的等轴超细/纳米晶双相PM-TiAl基合金Ti-45Al-5Nb（原子百分比）。在1000℃和1050℃下，应变速率为5×10⁻⁴s⁻¹至1×10⁻³s⁻¹时，研究了该合金的超塑性变形行为。对含高Nb的TiAl合金变形对其微观结构和力学行为的影响进行了表征和分析。结果表明，在应变速率为5×10⁻⁴s⁻¹时，该合金在1000℃下的极限抗拉强度为58.7MPa，在1050℃下为10.5MPa，而伸长率分别为121%和233%。该合金在1000℃和1050℃下均表现出超塑性伸长，应变速率敏感指数（m）分别为0.48和0.45。主要的软化机制是γ晶粒的动态再结晶；位错滑移和γ/γ界面孪晶是超塑性变形的原因。γ/γ界面孪晶的取向关系遵循经典关系：（001）//（110）。
