Zn对挤压态Mg-3Sn-1Ca合金耐蚀性的影响  

Effect of Zn on Corrosion Resistance of Extruded Mg-3Sn-1Ca Alloy

作　　者：贾征[1] 喻兵 付丽 乐启炽[2] JIA Zheng;YU Bing;FU Li;LE Qi-chi(College of Mechanical Engineering,Shenyang University,Shenyang 110044,China;Key Laboratory of Electromagnetic Processing of Materials,Ministry of Education,Northeastern University,Shenyang 110819,China)

机构地区：[1]沈阳大学机械工程学院,沈阳110044 [2]东北大学材料电磁过程研究教育部重点实验室,沈阳110819

出　　处：《表面技术》2023年第4期233-242,共10页Surface Technology

基　　金：辽宁省教育厅重点资助项目(LJKZ1171);中国博士后基金(2020M680978);辽宁省博士启动基金项目(2020-BS-260);国家自然科学基金(51974082)。

摘　　要：目的 提高挤压态Mg-3Sn-1Ca合金的耐腐蚀性能。方法 通过合金熔炼制备了Mg-3Sn-Ca(TX31)和Mg-3Sn-Ca-Zn(TXZ311)两种挤压态合金,利用XRD、金相、SEM、EDS、EBSD、析氢、电化学极化曲线和阻抗谱,分析了TX31和TXZ311两种合金的微观组织及耐腐蚀性能。结果 XRD和EDS结果表明,挤压态TX31和TXZ311两种合金中第二相均为CaMgSn相,TXZ311合金中由于Zn的添加,CaMgSn相增加且分布更加均匀。金相和EBSD结果表明,Zn的添加可以提高TX31合金的动态再结晶程度和{0002}基面织构强度,改善TX31合金中组织的不均匀性。从极化曲线上可得,腐蚀电位和腐蚀电流分别为-1.57V和6.95×10^(-5)A。添加Zn后,腐蚀电位升高(-1.49 V),腐蚀电流减小(1.02×10^(-5)A),表明合金耐蚀性提高。对比两种合金阻抗谱可发现,TXZ311合金具有比TX31合金更大的容抗弧,表明其表面的电荷转移电阻和表面膜的电阻最高,动态腐蚀过程中氧化产物膜具有较好的稳定性,有效阻碍了α-Mg基体的腐蚀。TX31合金析氢量和时间成正比,腐蚀速率为3.7mm/a。而TXZ311合金腐蚀速率仅为1.6mm/a,析氢量在腐蚀12 h后明显降低,表明合金表面形成了可以阻碍腐蚀进行的氧化膜。结论 Zn元素可以极大提高TX31合金的耐蚀性。这是由于添加Zn元素后,TXZ311合金腐蚀膜层间的黏附力增加,动态再结晶程度增高,晶粒组织更加均匀,{0001}基面织构强度增加。因此,TXZ311合金的耐蚀性远高于TX31合金。To improve the corrosion resistance of extruded Mg-3Sn-1Ca alloy.Two as-cast alloys Mg-3Sn-1Ca and Mg-3Sn-1Ca-1Zn were prepared by alloy melting using industrial pure Mg(99.9wt.%),pure Sn(99.9wt.%),Mg-25%Ca intermediate alloy and pure Zn(99.9wt.%).The as-cast alloy was homogenized(400×24℃h).After homogenization,the ingot was processed into a 47 mm×100 mm casting blank with a diameter of 47 mm×100 mm by a lathe.The processed casting blank was preheated to 300 and put into a mold hea℃ted to 300.Reverse extrusion was carried out on a 300℃-ton vertical hydraulic press.After extrusion,the diameter of the bar is 12 mm.The microstructure and corrosion resistance of TX31 and TXZ311 alloys were analyzed by XRD,Metallography,SEM,EDS,EBSD,Hydrogen Evolution,Electrochemical Polarization Curve and Impedance Spectroscopy.The XRD and EDS results show that the second phase in the extruded TX31 and TXZ311 alloys is CaMgSn phase.Due to the addition of Zn,the CaMgSn phase increases and distributes more evenly in the TXZ311 alloy.The Metallographic and EBSD results show that Zn addition can improve the dynamic recrystallization degree of the TX31 alloy and the texture strength of{0001}base plane,and improve the microstructure heterogeneity of the TX31 alloy.From the polarization curve,the corrosion potential and corrosion current are‒1.57 V and 6.95×10^(‒5) A respectively.After Zn was added,the corrosion potential increased(‒1.49 V)and the corrosion current decreased(1.02×10^(‒5) A),indicating that the corrosion resistance of the alloy was improved.By comparing the impedance spectra of the two alloys,it can be found that the TXZ311 alloy has a larger capacitive arc resistance than TX31 alloy,indicating that the charge transfer resistance on the surface and the resistance of the surface film are the highest,and the oxidation product film has a good stability during the dynamic corrosion process,which effectively prevents the corrosion ofα-Mg matrix.The amount of hydrogen evolution of the TX31 alloy is proportional

关 键 词：Mg-3Sn-1Ca Mg-3Sn-1Ca-1Zn 挤压态 CaMgSn相 动态再结晶 耐蚀性能 

分 类 号：TG174[金属学及工艺—金属表面处理]