热处理对含LPSO结构Mg-Y-Cu-Zr镁合金组织与腐蚀行为的影响

Effect of heat treatment on microstructure and corrosion behavior of Mg-Y-Cu-Zr magnesium alloy with LPSO structure

为研究长周期堆垛有序(LPSO)结构对镁合金腐蚀行为的影响,通过重力铸造制备了Mg-6.6Y-2.6Cu-1.2Zr(质量分数%)合金,并分别在420、440和460℃下固溶处理。借助SEM和XRD对合金显微组织和物相进行分析;通过腐蚀浸泡实验研究合金的耐蚀性能。结果表明,铸态Mg-6.6Y-2.6Cu-1.2Zr含有LPSO结构,随着固溶温度的升高,LPSO结构减少,晶粒尺寸增大,当固溶温度为460℃时,LPSO结构消失。不含LPSO结构的Mg-Y-Cu-Zr合金耐蚀性能优于含LPSO结构的该合金,而随着固溶温度的升高,含有LPSO结构的Mg-Y-Cu-Zr合金的耐蚀性能降低。此外,合金表现为严重的局部腐蚀行为。

Mg-6. 6Y-2. 6Cu-1. 2Zr（ mass fraction,%） alloy containing long period stacking ordered（ LPSO） structure was prepared by gravity casting,and then was solution treated at 420,440 and 460 ℃,respectively. The effect of LPSO structure on corrosion behavior of the magnesium alloy was investigated. The microstructure and phases of the alloy were studied by scanning electron microscopy（ SEM） and X-ray diffraction（ XRD）. Immersion tests were conducted to analyze the corrosion resistance of the alloy. The results show that LPSO structure can be observed in the as-cast Mg-6. 6Y-2. 6Cu-1. 2Zr alloy,and amount of the LPSO structure decreases and grain size of the alloy increases with increasing solution treatment temperature. The LPSO structure disappears after solution treating at 460 ℃. The alloy without LPSO structure exhibits much better corrosion resistance than that with LPSO structure. Moreover,the corrosion resistance of the alloy with LPSO structure decreases with increasing the solution treatment temperature. In addition,the alloy shows severely localized corrosion mode.