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采用光学显微镜和扫描电子显微镜对不同腐蚀剂腐蚀后的Mg-Nd-Zn-Zr镁合金铸态显微组织进行观察。结果表明,Mg-NdZn-Zr合金的铸态组织主要由α-Mg和晶界处的Mg_(12)(Nd,Zn)两相组成,另外还有小块状Mg12(Nd,Zn)相及近圆形的富Zr相区域。1号传统腐蚀剂(4 m L硝酸+96 m L乙醇)可较好显示组织;经2号腐蚀剂(12 g苦味酸+80 m L乙酸+80 m L蒸馏水+350 m L乙醇)腐蚀5 s和10 s后,组织发黑,晶界不明显,但可部分显示出富Zr相区,延长腐蚀时间到20 s,晶粒显现出来,发黑现象得到缓解,富Zr区域明显,但晶界附近出现大量气泡;3号腐蚀剂(60 m L乙二醇+20 m L乙酸+19 m L蒸馏水+1 m L硝酸)腐蚀组织表明,其对晶粒的显示效果明显好于2号,然而很难观察到富Zr区域。
The as-cast microstructure of Mg-Nd-Zn-Zr magnesium alloy after corrosion with different etchants was observed by optical microscope and scanning electron microscope. The results show that the as-cast microstructure of Mg-NdZn-Zr alloy is mainly composed of α-Mg and Mg_ (12) (Nd, Zn) phases in the grain boundaries, in addition to small Mg12 (Nd, Zn) Near-circular Zr rich phase region. The traditional etchant 1 (4 m L nitric acid + 96 m L ethanol) showed better tissue corrosion. After 2 s etchant (12 g picric acid + 80 m L acetic acid + 80 m L distilled water + 350 m L ethanol) for 5 s and After 10 s, the microstructure was black and the grain boundary was not obvious. However, the Zr-rich phase could be partially displayed. After prolonged the etching time to 20 s, the grains appeared and the black phenomenon was alleviated. The Zr-rich region was obvious. A large number of bubbles appeared. Corrosion of No. 3 etchant (60 m L ethylene glycol + 20 m L acetic acid + 19 m L distilled water + 1 m L nitric acid) showed that the effect on the grains was better than that of No. 2, however, it was difficult A Zr-rich region is observed.