稀土元素Nd对AZ80镁合金组织及耐蚀性能的影响

Effect of Nd addition on microstructure and corrosion resistance of AZ80 magnesium alloys

通过静态失重法、扫描电子显微镜及能谱分析、X射线衍射、电化学测试法等测试手段对添加不同含量（0～0．8％）稀土元素Nd的AZ80镁合金的铸态组织和耐蚀性能进行研究。结果表明：适量稀土Nd的加入细化了合金中的β-Mg17Al12相，并且其组织由连续网状分布变为断续状、均匀分布。稀土Nd与合金中Al结合形成颗粒状或块状的稀土相Al，Nd。本实验条件下，添加0．2％Nd提高了合金的腐蚀电位，降低了腐蚀电流密度，显著降低合金的腐蚀速率，使合金的耐腐蚀性能得到显著提高。

Effects of addition of different content of Nd on microstructure and corrosion resistance of as-cast AZ80 magnesium alloys in 3.5% NaC1 solution were investigated by means of scanning electron microscopy （SEM） with energy dispersive spectrometer （EDS） analysis, X-ray diffraction and electrochemical measurement. The results show that a new rare earth phase A13Nd is observed, the [3-MglTA112 phase in AZ80 alloy is fined and its distribution changes from continuous network to discontinuous dispersion after the addition of Nd into the alloys. The optimal modification effect is obtained when the Nd content in the alloys is 0. 2% , the corrosion rate of the alloy is 0. 35 mg·cm^-2 ·d-1 , only 64.81% of that of the AZ80 alloy without addition of Nd. Furthermore, the corrosion potential is enhanced and the corrosion current density is lowered significantly. The corrosion resistance of AZ80 magnesium is improved obviously by addition of Nb.