中间过渡元素对镁铝TIG熔敷焊显微组织的影响

Effect of intermediate elements on microstructure of TIG deposition welding of magnesium on aluminum

采用TIG焊在纯铝表面分别预先熔覆Ag,Zn,Ni,黄铜四种过渡物质,然后熔覆AZ31镁合金进行熔敷焊接,利用扫描电镜(SEM)对其组织进行分析和比较。结果表明:当在铝板上直接熔敷AZ31焊丝时,熔敷层的组织形态为柱状晶,镁铝元素的相互扩散形成Al_3Mg_2金属间化合物。当镁和铝分别添加Ag,Zn,Ni,黄铜熔敷焊接时,Ag和Zn元素可以阻止镁和铝元素的扩散,减少Mg/Al金属间化合物的生成,而Ni和黄铜未能有效的阻止镁和铝元素的扩散和金属间化合物的生成。

AZ31 magnesium alloy was deposited on aluminum alloy by TIG welding with filler metal added Ag,Zn,Ni and brass,respectively.The microstructures were analyzed by scanning electron microscope(SEM).The result shows that the morphology of the deposited layer is columnar crystal when AZ31 wire was deposited on the aluminum.The interdiffusion between magnesium and aluminum results in the presence of fragile Al_3 Mg_2 intermetallics.The formation of intermetallics was inhibited when Ag or Zn intermediate elements was added to the deposited layer.However,Ni and brass cannot effectively prevent the interdiffusion between magnesium and aluminum or the formation of intermetallic compounds.