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通过光学显微镜(OM)和扫描电子显微镜(SEM)观察了Mg-x Zn-y Gd(x=1~3,y=0~3)合金的挤压态组织及腐蚀形貌。结果表明:挤压态组织得到细化,平均晶粒尺寸从Mg-3Zn合金的(30±3)μm降到Mg-3Zn-1Gd合金的(10±2)μm,说明挤压过程发生了明显的动态再结晶,第二相沿挤压方向趋于带状分布。Mg-x Zn-y Gd合金的腐蚀以点蚀为主,在浸泡的时间段内,Mg-3Zn-2Gd合金的腐蚀速率最快,Mg-3Zn合金的腐蚀速率最低。经固溶处理后,Mg-3Zn-2Gd和Mg-3Zn-3Gd合金的腐蚀速率由原来的(0.605±0.025)和(0.352±0.021)mg/(cm2·h)分别降为(0.085±0.010)和(0.167±0.020)mg/(cm2·h)。随着Zn含量的增加,自腐蚀电流密度逐渐降低,高频区容抗半环逐渐增大;随着Gd含量的增加,自腐蚀电流密度逐渐先升高后降低,高频区容抗半环先降低后升高。Mg-3Zn合金的自腐蚀电流密度最小,为8.65×10-3(m A/cm2);而其Faraday电阻Rt最大,为3312Ω。
The microstructure and corrosion morphology of Mg-xZn-yGd (x = 1 ~ 3, y = 0 ~ 3) alloy were observed by optical microscope (OM) and scanning electron microscope (SEM) The results show that the microstructure is refined and the average grain size decreases from (30 ± 3) μm in Mg-3Zn alloy to (10 ± 2) μm in Mg-3Zn-1Gd alloy, indicating that the extruding process is obvious Of the dynamic recrystallization, the second phase along the extrusion direction tends to strip distribution. The corrosion of Mg-x Zn-y Gd alloy is dominated by pitting corrosion. The corrosion rate of Mg-3Zn-2Gd alloy is the fastest and the corrosion rate of Mg-3Zn alloy is the lowest during the immersion time. The corrosion rates of Mg-3Zn-2Gd and Mg-3Zn-3Gd alloys decreased from (0.605 ± 0.025) and (0.352 ± 0.021) mg / (cm2 · h) to (0.085 ± 0.010) And (0.167 ± 0.020) mg / (cm2 · h), respectively. With the increase of Zn content, the self-corrosion current density gradually decreases and the capacitance half-ring capacitance gradually increases in the high-frequency region. With the increase of Gd content, the self-corrosion current density first increases and then decreases, First decrease and then increase. The self-corrosion current density of Mg-3Zn alloy is the smallest, 8.65 × 10-3 (m A / cm2), while the Faraday resistance Rt is the largest, 3312Ω.