Macro-micro behaviors of Ti-22Al-26Nb alloy during warm tension

作者：Zhang, Xiao-li; Yan, Si-liang^*; Meng, Miao; Li, Ping^*

来源：Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing , 2022, 850: 143580.

DOI：10.1016/j.msea.2022.143580

• Macro-micro behaviors
• Ti-22Al-26Nb alloy
• Warm tension
• Fracture mode
• Deformation coordination mechanisms

In this paper, the plastic flow rules and fracture evolution mechanisms of the nearly O + B2 Ti-22Al-26Nb alloy during warm tension have been studied within a wide temperature range of 20-800 degrees C. The macro-micro deformation behaviors of the material have been investigated by means of SEM, EBSD and TEM. It is found that the stress-strain curve at 400 degrees C exhibits serrated patterns, indicating the occurrence of dynamic strain aging at mild temperature. The overall yield strength decreases and the uniform elongation increases with the tem-perature in general. However, an unexpected peak of yield strength and also an unexpected valley of uniform elongation are exhibited at 600 degrees C. Additionally, the uniform elongation shows a positive correlation with strain rate at 600 degrees C. With the comprehensive analyses of fracture surface characteristics, the morphological variation of the constituent phases and the dislocation structure evolution, the causations of the above phenomena are further explained as follows. The B2 phase is mainly responsible for deformation coordination between O laths with the original {110}(B2)parallel to(001)(O) orientation barely changed, and act as a media for propagating localized slip deformation to O grains. The abnormal mechanical responses at 600 degrees C are mainly attributed to the change of fracture mode caused by the precipitation of fine acicular O grains, while the softening mechanism at 800 C is mainly dominated by the dynamic globularization of the O phase.

• 单位
  西北工业大学; 华中科技大学