纯铜作中间层的镁合金与不锈钢扩散-钎焊接头区的微观结构特征

摘要

A novel joining method,double-stage diffusion-brazing of an AZ31 magnesium alloy and a 304L austenitic stainless steel,was carried out using a pure copper interlayer.The solid-state diffusion bonding of 304L to copper was conducted at 850 ℃ for 20 min followed by brazing to AZ31 at 520 ℃ and 495 ℃ for various time.Microstructural characteristics of the diffusion-brazed joints were investigated in detail.A defect flee interface of Fe-Cu diffusion area appeared between the Cu alloy and the 304L steel.Cu-Mg reaction products were formed between AZ31 and Cu alloys.A layered structure including AZ31/Cu-Mg compounds/Cu/Fe-Cu diffusion layer/304L was present in the joint.With time prolonging,the reduction in the width of Cu layer was balanced by the increase in the width of Cu-Mg compounds zone.Microhardness peaks in the zone between AZ31 and Cu layer were attributed to the formation of Mg-Cu compounds in this zone.%以纯铜作中间层采用一种新型的两步式扩散-钎焊方法对AZ31镁合金和304L奥氏体不锈钢进行连接.304L与铜的固态扩散连接在850℃下进行20 min,随后与镁合金在520℃和495℃进行不同时间的钎焊.对扩散-钎焊接头区的微观结构特征进行研究.在铜与304L钢之间形成没有缺陷存在的Fe-Cu扩散界面.在AZ31和铜之间形成Cu-Mg反应物.在接头处出现包含AZ31/Cu-Mg化合物/Cu/Fe-Cu扩散层/304L的层状结构.随着时间的延长,铜层的宽度降低,而Cu-Mg化合物层的宽度增加.形成的Mg-Cu化合物使AZ31和铜层之间的区域出现显微硬度的峰值.