摘要
镁合金因其轻量化特性和优良的力学性能,在壳体和支架类零部件上具有广泛的应用。然而,镁合金的电化学活性较大,且腐蚀产物膜疏松多孔,严重影响了零部件的服役性能。为此,本工作以典型商用镁合金AZ91为对象,研究Ca(0.1%,质量分数,下同)和不同含量Sr (0%、0.05%、0.15%、0.25%)复合添加后合金组织与耐腐蚀性的变化规律。结果表明:当0.1%Ca和0.15%Sr复合添加后,合金的组织最均匀细小,且耐腐蚀性能最好,其自腐蚀电位达到-1.484 V。随着Sr含量的增加,合金的蔷薇组织有所细化,同时组织中的Mg_(17)Al_(12)含量有所降低,而Al_(4)Sr和Al_(2)Ca相含量在0.25%Sr时显著增加。在高Sr含量中半连续的阴极相Mg_(17)Al_(12)逐渐被凝固界面前沿的Al_(4)Sr和Al_(2)Ca相阻断,并在相间产生了较多腐蚀通道,使得合金的耐蚀性能下降。适当的Sr(0.15%)在不明显改变Mg_(17)Al_(12)相分布连续的同时,生成了少量Al_(4)Sr和Al_(2)Ca阴极相,且明显细化了合金组织,使得腐蚀较为均匀和缓慢,从而提高了合金的耐蚀性能。此外,对Ca、Sr复合添加下的合金腐蚀机理进行了分析。
Magnesium alloys have a wide range of applications in shell and bracket parts due to their lightweight properties and excellent mechanical properties.However,the electrochemical activity of magnesium alloys is relatively high,and the corrosion product film is porous and loose,which significantly influences the service performance of the components.In this study,AZ91 magnesium alloy was employed as the research object to examine the impact of combined additions of Ca(0.1%)and varying contents of Sr(0%,0.05%,0.15%,0.25%)on the alloy microstructure and corrosion resistance.The results show that when 0.1Ca and 0.15Sr are combined,the alloy exhibits the most uniform and refined microstructure,and the optimal corrosion resistance with a self-corrosion potential of-1.484 V.As the Sr content increases,the rose-like microstructure of the alloy is refined,and the content of Mg_(17)Al_(12)in the microstructure is observed to decrease.Conversely,the concentrations of the Al 4Sr and Al_(2)Ca phases demonstrate a significant increase at 0.25% Sr.In the high Sr content,the semi-continuous cathodic phase Mg_(17)Al_(12) is gradually blocked by the Al_(4)Sr and Al_(2)Ca phases at the solidification interface front,this results in the formation of additional corrosion channels between these phases,leading to a decrease in the corrosion resistance of the alloy.The addition of an appropriate Sr(0.15%)element gene-rates a minimal quantity of both Al_(4)Sr and Al_(2)Ca cathodic phases,which do not markedly change the distribution of the Mg_(17)Al_(12) phases,and significantly refines the alloy microstructure,resulting in more uniform and slower corrosion,thereby enhancing the corrosion resistance of the alloy.Furthermore,an in-depth analysis of the corrosion mechanism of the alloy with the combined addition of Ca and Sr was conducted.
作者
吴霜
胡平
刘文君
高雪琴
王维青
宋江凤
王辉
蒋斌
WU Shuang;HU Ping;LIU Wenjun;GAO Xueqin;WANG Weiqing;SONG Jingfeng;WANG Hui;JIANG Bin(School of Materials Science and Engineering,Chongqing University of Technology,Chongqing 400054,China;School of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Southwest Technology and Engineering Research Institute,Chongqing 400039,China)
出处
《材料导报》
北大核心
2025年第20期186-194,共9页
Materials Reports
基金
国家重点研发计划(2021YFB3701000,2022YFB3709300)
重庆市教委科学技术研究计划(KJQN202201136)
重庆市技术创新与应用发展专项重点项目(CSTB2022TIAD-DEX0011)
重庆理工大学研究生创新项目(gzlcx20233006)
大学生创新创业训练计划项目(202311660002)。
