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研究了0.5,1.0和1.5(质量分数,%,下同)的Ca对铸态AZ91镁合金微观组织和耐蚀性的影响。利用OM、SEM/EDS和XRD观察金相组织、进行微观分析和确定相组成。分别采用静态失重腐蚀、电化学腐蚀和盐雾腐蚀对不同成分的AZ91合金进行实验。结果表明,0.5Ca的存在没有形成任何新的金属间相,而是通过溶解于第二相和基质中抑制β-Mg17Al12相的不连续沉淀。AZ91-1.0Ca合金耐蚀性最好。AZ91-1.0Ca和AZ91-1.5Ca合金中出现了骨状的Al4Ca相,并且β相尺寸显著下降。在AZ91-1.0Ca合金中,β相分布十分均匀。因此,可以认为,随着不同含量Ca的加入,铸态AZ91镁合金耐蚀性的变化是由于其微观组织的变化而引起的。
The effects of Ca on the microstructure and corrosion resistance of as-cast AZ91 magnesium alloy were studied at 0.5, 1.0 and 1.5 (mass fraction,%, the same below). The microstructure was observed by OM, SEM / EDS and XRD, and the microstructure and phase composition were determined. Respectively, static weightlessness corrosion, electrochemical corrosion and salt spray corrosion on different composition of AZ91 alloy experiments. The results show that the presence of 0.5Ca does not form any new intermetallic phases but inhibits the discontinuous precipitation of the β-Mg17Al12 phase by dissolution in the second phase and the matrix. AZ91-1.0Ca alloy corrosion resistance of the best. Bone Al4Ca phase appeared in AZ91-1.0Ca and AZ91-1.5Ca alloys, and the β phase size decreased significantly. In AZ91-1.0Ca alloy, β phase distribution is very uniform. Therefore, it can be considered, with the addition of different Ca content, the change of corrosion resistance of as-cast AZ91 magnesium alloy is due to its microstructure changes.