J. Mater. Sci. Technol. ›› 2021, Vol. 94: 1-9.DOI: 10.1016/j.jmst.2021.02.061

• Research Article •     Next Articles

Effects of heating rate on the alloy element partitioning and mechanical properties in equiaxed α+β Ti-6Al-4V alloy

Jinhu Zhanga,c,1,*(), Hongtao Jua,b,c,1, Haisheng Xua,b,c, Liang Yanga,c, Zhichao Menga,b,c, Chen Liud, Ping Sund, Jianke Qiua,b,c,**(), Chunguang Baia,b,c, Dongsheng Xua,b,c,**()   

  1. aInstitute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
    bSchool of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China
    cShi-changxu Innovation Center for Advanced Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
    dSafety Evaluation Center, Shenyang Research Institute of Chemical Industry Co., Ltd., Shenyang 110141, China
  • Received:2020-11-02 Revised:2021-02-09 Accepted:2021-02-19 Published:2021-12-20 Online:2021-05-19
  • Contact: Jinhu Zhang,Jianke Qiu,Dongsheng Xu
  • About author:dsxu@imr.ac.cn (D. Xu).
    ** School of Materials Science and Engineering, Univer-sity of Science and Technology of China, Shenyang 110016, China. E-mail addresses: jkqiu@imr.ac.cn (J. Qiu),
    *Institute of Metal Research, Chinese Academy of Sci-ences, Shenyang 110016, China. E-mail addresses: jinhuzhang@imr.ac.cn (J. Zhang),
    First author contact:

    1Both the authors equally contributed to this work.

Abstract:

The effects of heating rate on the alloy element partitioning and mechanical properties during the phase transformation of α→β in Ti-6Al-4 V alloy under solution treatment have been investigated by the experiments and phase field simulations, which reveal the evolutions of microstructure and compositions at the non-equilibrium state and well verify the experimental results. The specific results indicate that the compositions measured through electron probe micro-analysis (EPMA) under a lower heating rate are close to the equilibrium ones corresponding to the solution temperature. Heating up to the target solution temperature, as the heating rate increases, the Al content decreases and V increases in the primary α (αp) grain with a larger size, the volume fraction of αp increases and the composition gradient between αp and β phases gets steeper. The interrelated relationship among the diffusion, compositions, solution temperature and free energy of the system has been discussed in detail. Moreover, increasing the heating rate (~20.0 K/min) may help to improve the mechanical properties of the alloy by mainly adjusting the αpt volume fractions, αp particle size and secondary α (αs) size during the process of heating up to the solution temperature. These results may shed some light on the optimization of the knowledge-based heat treatment route.

Key words: Heating rate, Alloying element partitioning, Microstructure morphology, Mechanical properties