Effect of Er-Rich Precipitates on Microstructure and Electrochemical Behavior of the Al–5Zn–0.03In Alloy

Abstract

The effect of Er-rich precipitates on microstructure and electrochemical behavior of the Al–Zn–In anode alloy is investigated. The results showed that with the increase in Er content, the microstructure was refined, the amount of interdendritic precipitates gradually increased, and the morphology changed from discontinuous to continuous network gradually. With the addition of Er element, the self-corrosion potential of the Al–5Zn–0.03In–xEr alloy moved positively, the self-corrosion current density decreased, and the corrosion resistance increased. When the Er content was less than 1 wt.%, the addition of Er improved the dissolution state of the Al–5Zn–0.03In–xEr alloy, and increased the current efficiency of the Al–5Zn–0.03In–xEr alloy. When the Er content was more than 1 wt.%, the current efficiency was reduced. The major precipitate of the alloy was Al3Er. According to the element composition of Al3Er in the Al–Zn–In–Er alloy, the simulated-segregated-phase alloy was melted to explain the effect of Al3Er segregation on the electrochemical behavior of alloys, and the polarization curve and AC impedance spectrum of the simulated-segregated-phase alloy and the Al–Zn–In alloy were measured. The results showed that Al3Er was an anodic segregation phase in the Al–Zn–In–Er alloy, and the preferential dissolution of the segregation phase would occur in the alloy, but the Al3Er phase itself was passivated in the dissolution process, which inhibited the further activation of the dissolution reaction of the Al–Zn–In–Er alloy to a certain extent.

Kinetic Mechanism of Hydrogen Absorption of AA6111 Alloys Melt

“…[H]→[H] (aq) (3) where [H] is the atomic state of hydrogen, and [H] (aq) is dissolved hydrogen in aluminum melts.…”

“…The quality requirements of aluminum alloy are becoming increasingly stringent with the wide application of aluminum alloy in the automobile, aerospace, and electronics industry, among others [1][2][3][4][5][6]. Aluminum alloy melts are very easily react with water vapor in the air, and absorb hydrogen during the melting process; this leads to pinhole and porosity defects in the casting and seriously reduces the tensile strength, elongation, and fatigue resistance of the aluminum alloy.…”

Effect of Heat Treatment on Microstructural Evolution and Microhardness Change of Al-5Zn-0.03In-1Er Alloy

“…According to our previous research [14][15][16], Al-5Zn-0.03In-xEr alloys have good electrochemical properties and it is found that when the content of Er is about 1 wt.% the current efficiency of Al-Zn-In-Er alloy is the best; therefore, we chose Al-5Zn-0.03In-1Er as the experimental alloy. In this work, a master alloy of Al-10 wt.% In was produced by WKDHL-II non-consumable vacuum arc-melting in argon from 99.99 wt.% Al and 99.99 wt.% In.…”

“…As the addition amount rises, the refining effect gradually decreases and the corrosion resistance of the alloy increases. Another study showed that the current efficiency of Al-Zn-In-xEr alloys was increased when the Er content was less than 1 wt.% [16].…”