稀土Nd对AZ91镁合金组织及耐蚀性的影响

Influence of Nd addition on microstructure and corrosion resistance of AZ91 Mg alloy

通过OM、XRD、SEM等测试手段研究了添加稀土Nd前后的AZ91镁合金的组织形貌，并在w（NaCl）=3．5％的水溶液中进行了0～96h的失重腐蚀测验。结果表明，稀土元素Nd的加入使AZ91镁合金中β-Mg17Al12相的数量明显减少，并且由粗大连续网状分布转变为断续状、均匀分布。同时，Nd与合金中Al结合生成杆状或颗粒状的稀土相A13Nd。本试验条件下，添加w（Nd）=0．85％的AZ91镁合金的平均腐蚀速率为0．45mg／（cm2·d），仅为AZ91镁合金腐蚀速率的59．07％，提高了该合金的耐蚀性能。

The microstructure of AZ91 Mg alloy before and after Nd addition were re- searched by means of OM, XRD and SEM, and the average corrosion rate was tested in w（NaCl） =3.5% solution for 0- 96 h. The results show that as Nd is added, 13-Mg17A112 phases in the AZ91 Mg alloy become much fewer and the morphology of the AZ91 Mg alloy changes from the continuous network to discontinuous and evenly disperse distribution. Mean- while, Nd and Al in the AZ91 Mg alloy are combined to rod-like or granular Al3 Nd phases. For the AZ91 Mg alloy with wNd） =0.85% ,the average corrosion rate is 0.45 mg/（ cm2 d）, only 59.07% of that of AZ91 Mg alloy, enhancing the corrosion resistence property.