快速凝固及Si元素对Mg-Al合金组织与腐蚀性能的影响  

Effect of Rapid Solidification and Si Element on Microstructure and Corrosion Property of Mg-Al Magnesium Alloy

作　　者：赵聃[1] 梁伟[1] 樊强[1] 周康康[1] 刘沈阳 王红霞[1] 

机构地区：[1]太原理工大学材料科学与工程学院,山西太原030024

出　　处：《热加工工艺》2012年第17期1-5,共5页Hot Working Technology

基　　金：国家自然科学基金(5117536);太原市大学生创新创业专项基金(110148056);山西省青年科技研究基金(2008021033)

摘　　要：采用磁悬浮熔炼真空吸铸法制备了快速凝固态AZ91D合金,采用常规铸造法制备了普通铁模铸型浇注的不同成分的Mg-Al合金。通过OM、SEM、EDS及XRD等现代检测方法,分析了不同凝固条件下Mg-Al合金的组织形貌、相组成和腐蚀形貌,研究了冷却速度和元素微合金化对Mg-Al合金组织及腐蚀性能的影响。结果表明:磁悬浮真空吸铸快速凝固AZ91D合金的α-Mg枝晶明显细化,尺寸由200μm降到20μm左右。β-Mg17Al12相则沿晶界形成连续网状。添加微量Si元素,α-Mg枝晶尺寸略有下降,晶内出现汉字状的Mg2Si相,促进β相的网状化。加快冷却速率,增加Al含量,添加微量Si元素均能提高合金的耐蚀性能。铜模吸铸AZ91D合金的自腐蚀电位Ecorr比铸铁模铸AZ91D合金正移0.375V,自腐蚀电流降低了1个数量级。Mg12Al-0.7Si合金的Ecorr比Mg12Al合金的正移0.526V,自腐蚀电流密度比Mg12Al合金降低1个数量级,比AZ91D合金降低2个数量级。The rapidly solidified AZ91D alloys were successfully prepared by means of suspended melting-copper mold suction casting. The as-cast AZ91D alloys mad Mgl2Al magnesium alloys with different component were produced by iron mold casting. The microstructure,phase and corrosion morphology of Mg-Al magnesium alloys trader different solidification conditions were studied by OM,SEM,EDS and X-ray diffraction （XRD）. Effects of cooling rate and micro-alloying on the microstructure and corrosion resistance of Mg-Al magnesium alloys were also investigated. The results show that the rapidly solidified sample of AZ91D alloys can obtain finer grains （20 ~m）, comparing with that of as-cast alloy（200 ixm）, and the morphology of [^-Mg17Al12 phase can change from discontinuous network to continuous one. Adding 0.7%Si to Mgl2Al alloy results in the slight decrease of the et-Mg dendrite size, and present the coarse Chinese script Mg2Si phase in the ct-Mg grain, to form reticular [3-MgnAl^2 phase. Electrochemical test show that the increased cooling speed, AI content and added Si element improve obviously alloy＇s corrosion resistance. The corrosion potential E~,, of rapidly solidified AZ91D alloy drifts ＋0.375V comparing with as-cast AZ91D alloy, and the corrosion current drops an order of magnitude. Furthermore, the corrosion potential Ecom of Mg12Al-0.7Si alloy drifts ＋0.526V comparing with Mgl2Al alloy and the corrosion current of Mgl2Al-0.7Si alloy drops an order of magnitude than Mgl2Al alloy and two orders of magnitude than AZ9 I D alloy.

关 键 词：快速凝固 元素微合金化 微观组织 腐蚀性能 

分 类 号：TG292[金属学及工艺—铸造]