Mg-5Al-2Zn-0.2Mn alloys with Y contents of 0, 0.2, 0.3, 0.4, and 0.5 wt.% were prepared by gravity casting. The influence of Y content on magnesium alloys’ fine texture and corrosion behavior was studied by detections. The experimental results indicate that the magnesium metal structure without Y mainly consists of the magnesium matrix phase and continuous or semi-continuous β-phase Mg17(Al, Zn)12 distributed in the grain boundary and matrix. The addition of Y disrupted the continuity of βMg17 (Al, Zn)12. When Y was added 0.5 wt.%, the mesh β-phase was destroyed and distributed in uniform granular form, and a new phase (MgAl4Y) was formed. Salt spray and electrochemical tests show that the corrosion behavior is the greatest while the alloy is III. XRD data show that magnesium alloy’s metal surface membrane layer mainly consists of MgO, MgOꞏH2O, and contains a bit of MgCO3, Al2O3, and Y2O3.
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