【摘要】 对未变质、Na变质和Sr变质Al-11.7%Si合金在4%硫酸水溶液中进行了失重腐蚀试验,分别用扫描电子显微镜和光学显微镜观察试样表面腐蚀形貌和纵深腐蚀状况。结果表明,在强酸环境中未变质合金的耐蚀性最好,Sr变质合金次之,Na变质合金最差。浸蚀360h之前,三种合金的腐蚀行为都表现为均匀腐蚀。360h后,点蚀成为变质合金腐蚀行为的主要特征。Sr变质合金蚀孔深、横向腐蚀缝不发达。而Na变质合金蚀孔略浅,但横向腐蚀缝相当发达。480h后Na变质合金中横向腐蚀缝趋于相互贯通导致剥蚀发生。Na变质合金与Sr变质合金腐蚀行为的差异可能与合金组织中枝晶!的排列位向有关。更多还原

【Abstract】 Weight loss test in 4% sulfuric acid aqueous solution bath was used to investigate the corrosion resistance of Al-11.7% Si alloys with no modification, sodium modification, or strontium modification. And SEM and optical microscopy were used to observe the surface and depth corrosion morphologies of the alloys respectively. The results showed that the corrosion-resistance of the alloy with no modification was the best, Sr-modified alloy the second and Na-modified alloy the worst. In the former 360 hours duration, the characteristics of all the three alloys were uniform corrosion. However, after 360 hours duration, pitting corrosion became the typical characteristic of the modified alloys. The depth of the pitting holes in Sr-modified alloy is larger than that in Na-modified alloy, but the transverse corrosion channel in Sr-modified alloy is far less than that in Na-modified alloy. After 480 hours duration, the transverse corrosion channels in Na-modified alloy trended to become interconnected inch by inch, which resulted in a severe exfoliation. The corrosion difference between Sr-modified alloy and Na-modified alloy might be related to the orientation of ?琢 dendrites in the alloys.更多还原