Acta Metallurgica Sinica (English Letters) ›› 2022, Vol. 35 ›› Issue (1): 163-175.DOI: 10.1007/s40195-021-01299-x

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3D Fe-Rich Phases Evolution and Its Effects on the Fracture Behavior of Al-7.0Si-1.2Fe Alloys by Mn Neutralization

Dong-Fu Song1,2, Yu-Liang Zhao3, Zhi Wang1, Yi-Wang Jia2, Dao-Xi Li1, Ya-Nan Fu4, Da-Tong Zhang1, Wei-Wen Zhang1()   

  1. 1National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials, South China University of Technology, Guangzhou, 510641, China
    2Guangdong Provincial Key Laboratory of Metal Toughening Technology and Application, Institute of New Materials, Guangdong Academy of Sciences, Guangzhou, 510650, China
    3School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, China
    4Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China
  • Received:2021-05-27 Revised:2021-06-26 Accepted:2021-06-28 Online:2022-01-10 Published:2021-08-19
  • Contact: Wei-Wen Zhang
  • About author:Wei-Wen Zhang, mewzhang@scut.edu.cn

Abstract:

The evolution of the 3D Fe-rich phases of Al-7.0Si-1.2Fe alloys with different Mn contents was visualized and characterized using synchrotron X-ray computed tomography, and the effect of Fe-rich phases with typical morphologies on the fracture behavior during tensile testing was analyzed. The results showed that the Fe-rich phase changed from platelet-like β-Al5FeSi into α-Al15(FeMn)3Si2 with various morphologies after the addition of Mn. The Mn addition not only significantly reduced the volume fraction, equivalent diameter and interconnectivity of the Fe-rich phase but also greatly increased the sphericity, surface thickness, and distribution of the mean curvature and surface thickness. Furthermore, the equivalent diameter of α-Al15(FeMn)3Si2 had an inverse exponential function relationship with its sphericity. The 3D morphology of α-Al15(FeMn)3Si2 can be summarized as massive and regular polyhedrons, hollow and regular polyhedrons, and multibranched polyhedrons. The fraction of the different 3D morphologies in each alloy is related to the Mn content, where excess Mn increased the number and volume fraction of the large Fe-rich particles with a low sphericity. The ductility of each alloy was significantly improved by the addition of Mn but gradually decreased when the Mn/Fe ratio exceeded 1.2. The increase in large α-Al15(MnFe)3Si2 with a low sphericity was the main reason for the decreased ductility of alloys with a high Mn content.

Key words: Synchrotron X-ray tomography, Fe-rich phase, 3D morphology, Fracture behavior