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采用金相显微镜(OM)、扫描电镜(SEM)对Mg-Y合金与纯镁的铸态凝固组织进行了观察,并采用X射线衍射仪(XRD),能谱分析仪(EDS)对合金在凝固过程中形成的相进行了分析,利用析氢法及电化学方法研究了Mg-Y合金与纯镁在3.5%的NaCl溶液中的腐蚀行为。结果表明,纯镁的晶粒比较粗大,合金的晶粒比纯镁小,合金由灰白色的初生α相和深色的共晶组织构成,以及少量呈颗粒状弥散分布在基体中Mg24Y5相。析氢法中,试样在浸泡了8 h左右时,合金腐蚀速率是纯镁的2.85倍,纯镁在浸泡7 h后pH值稳到10.4左右,而合金的pH值变化较快,在1.5 h后就已经达到了10.4,最后稳定在11.2左右。从腐蚀形貌看,纯镁的腐蚀较浅,沿表面扩展,呈纹理状,合金则呈现明显的局部腐蚀特征,表面形成了严重的腐蚀坑。3.5%的NaCl溶液中测得的极化曲线可以得出,合金的腐蚀电流Icorr(4.05×10-4A.cm-2)比纯镁Icorr(6.81×10-5 A.cm-2)要高的多。
The as-cast solidified microstructure of Mg-Y alloy and pure Mg was observed by OM and SEM, and the as-cast microstructure of Mg-Y alloy and pure Mg was observed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) The phase formed during solidification was analyzed. The corrosion behavior of Mg-Y alloy and pure magnesium in 3.5% NaCl solution was studied by means of hydrogen evolution and electrochemical methods. The results show that the grains of pure magnesium are relatively coarse, and the grains of the alloy are smaller than the pure magnesium. The alloy is composed of the gray primary α phase and the dark eutectic structure, and a small amount of Mg24Y5 phase dispersedly dispersed in the matrix. In the hydrogen evolution method, the corrosion rate of the alloy is 2.85 times that of the pure magnesium when the sample is soaked for about 8 h, and the pH value of the pure magnesium reaches about 10.4 after soaking for 7 h, while the pH value of the alloy changes rapidly. After 1.5 h After it has reached 10.4, and finally stabilized at 11.2 or so. From the corrosion morphology, pure magnesium corrosion shallow, along the surface expansion, texture, the alloy showed obvious local corrosion characteristics, the surface formed a serious pit corrosion. The polarization curve measured in 3.5% NaCl solution shows that the corrosion current Icorr (4.05 × 10-4A.cm-2) is higher than that of pure MgO (6.81 × 10-5 A.cm-2) More.