Mg-39Pb-11.5Al-1B-0.4Sc合金在3.5%NaX(X=F,Cl,Br,I)溶液中的腐蚀行为

Corrosion behaviors of Mg−39Pb−11.5Al−1B−0.4Sc alloy in 3.5 wt.%NaX(X=F,Cl,Br and I)solutions

采用熔融法制备Mg−39Pb−11.5Al−1B−0.4Sc合金,并利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、极化曲线测试和电化学阻抗谱(EIS)分析合金在3.5%(质量分数)NaX(X=F,Cl,Br,I)溶液中的腐蚀行为和机理。结果表明,Mg−39Pb−11.5Al−1B合金的组成相为α-Mg、Mg_(2)Pb、Mg_(17)Al_(12)和AlB_(2)。Sc的加入可以显著细化显微组织。Mg−39Pb−11.5Al−1B−0.4Sc合金在NaX溶液中的耐腐蚀性顺序为NaCl<NaBr<NaI<NaF。在NaX(X=Cl,Br,I)溶液的腐蚀过程中Mg先被溶解,然后Mg_(2)Pb被溶解,最后导致Mg_(17)Al_(12)从基体脱落。Mg和Mg_(2)Pb腐蚀产物分别为Mg(OH)_(2)和MgO。

Mg−39Pb−11.5Al−1B−0.4Sc alloy was prepared by melting method,and the corrosion behaviors and mechanisms in 3.5 wt.%NaX(X=F,Cl,Br,and I)solutions were analyzed using X-ray diffraction(XRD),scanning electron microscopy(SEM),polarization curve test,and electrochemical impedance spectroscopy(EIS).The results show that the phases of Mg−39Pb−11.5Al−1B alloy areα-Mg,Mg_(2)Pb,Mg_(17)Al_(12) and AlB_(2).The addition of Sc can refine the microstructure significantly.The corrosion resistance of Mg−39Pb−11.5Al−1B−0.4Sc alloy in NaX solutions is in the order of NaCl<NaBr<NaI<NaF.During the corrosion process in NaX(X=Cl,Br,and I)solutions,Mg is first dissolved,then Mg_(2)Pb is dissolved,and finally Mg_(17)Al_(12) is fallen off from matrix.The corrosion products of Mg and Mg_(2)Pb are Mg(OH)_(2) and MgO,respectively.