Microstructures and properties in surface layers of Mg-6Zn-1Ca magnesium alloy laser-clad with Al-Si powders  

Mg-6Zn-1Ca合金激光熔覆Al-Si层的组织与性能（英文）

作　　者：Xiao-lin ZHANG Ke-min ZHANG Jian-xin ZOU 张晓林;张可敏;邹建新(上海工程技术大学材料工程学院,上海201620;上海交通大学材料科学与工程学院轻合金精密成型国家工程研究中心,上海200240)

机构地区：[1]School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China [2]National Engineering Research Center of Light Alloys Net Forming, School of Materials Science and Engineering,Shanghai Jiao Tong University, Shanghai 200240, China

出　　处：《Transactions of Nonferrous Metals Society of China》2018年第1期96-102,共7页中国有色金属学报（英文版）

基　　金：Project(2016YBF0701205) supported by the National Key Research and Development Program of China;Projects(51271121,51471109) supported by the National Natural Science Foundation of China;Project(13KY0501) supported by Shanghai University of Engineering Science Innovation Fund for Graduate Students,China

摘　　要：Laser surface cladding with Al-Si powders was applied to a Mg-6Zn-1Ca magnesium alloy to improve its surface properties.The microstructure,phase components and chemical compositions of the laser-clad layer were analyzed by using X-ray diffractometry(XRD),scanning electron microscopy(SEM)and energy dispersive spectrometry(EDS).The results show that the clad layer mainly consists ofα-Mg,Mg2Si dendrites,Mg17Al12and Al3Mg2phases.Owing to the formation of Mg2Si,Mg17Al12and Al3Mg2intermetallic compounds in the melted region and grain refinement,the microhardness of the clad layer(HV0.025310)is about5times higher than that of the substrate(HV0.02554).Besides,corrosion tests in the NaCl(3.5%,mass fraction)water solution show that the corrosion potential is increased from-1574.6mV for the untreated sample to-128.7mV for the laser-clad sample,while the corrosion current density is reduced from170.1to6.7μA/cm2.These results reveal that improved corrosion resistance and increased hardness of the Mg-6Zn-1Ca alloy can be both achieved after laser cladding with Al-Si powders.采用激光熔覆Al-Si粉体以提高Mg-6Zn-1Ca合金的表面性能,并采用X射线衍射(XRD)、扫描电镜(SEM)和能谱(EDS)技术研究熔覆层的相组成、组织结构和化学成分。结果表明,熔覆层主要由α-Mg、Mg_2Si枝晶、Mg_(17)Al_(12)和Al_3Mg_2相组成。由于生成了Mg_2Si、Mg_(17)Al_(12)和Al_3Mg_2金属间化合物以及快速熔凝的晶粒细化作用,熔覆层的显微硬度(HV_(0.025) 310)比基体硬度(HV_(0.025) 54)高近5倍。同时,在3.5%NaCl(质量分数)水溶液中的腐蚀性能测试显示,腐蚀电位从基体的-1574.6 mV上升到了熔覆后的-128.7 mV,而腐蚀电流密度则从基体的170.1μA/cm^2降至熔覆后的6.7μA/cm^2。这些研究结果显示,激光熔覆Al-Si粉体可以显著提高Mg-6Zn-1Ca合金表层的硬度和耐蚀性。

关 键 词：laser cladding Mg-6Zn-1Ca alloy microstructure hardness corrosion resistance 

分 类 号：TG174.4[金属学及工艺—金属表面处理]