1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. Advance Research Center, Central South University, Changsha 410083, China
Abstract：Cr and Zr microalloyed Al-Zn-Mg-Cu-Yb alloys were prepared by ingot metallurgy. The precipitation characteristics of solidified crystalline phase in Cr or Zr microalloyed Al-Zn-Mg-Cu-Yb alloys and its influence mechanism on the corrosion behavior of the as-cast alloys were studied by electrochemical test and static corrosion experiment, combined with the observation and analysis of X-ray diffraction, optical microscope, scanning electron microscope and transmission electron microscope. The results show that the dendrites of the three as-cast Al-Zn-Mg-Cu-Yb alloys are mainly composed of Al2CuMg (S phase), Al8Cu4Yb and Mg(Zn,Cu,Al)2 (Sigma phase). The addition of Cr or Zr leads to the increase of Cu content in Sigma phase, the increase of potential of Sigma phase and the decrease of potential difference between dendrites and aluminum matrix, which can improve the corrosion properties of the as-cast alloys. Compared with Al-Zn-Mg-Cu-Yb and Al-Zn-Mg-Cu-Yb-Cr alloys, Al-Zn-Mg-Cu-Yb-Zr alloy has higher corrosion resistance, and the corrosion form changes from intergranular corrosion to uniform corrosion.
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2022, Vol. 27 
