冷轧焊接制备Ag/Al双金属材料的扩散和相转变

摘要

通过轧制Al条和Ag条制备Ag/Al双金属条.为使Al和Ag条之间发生冷焊,对表面进行处理并设置不同的轧制压下量.实验表明:发生冷焊的最小临界轧制厚度压下量为70％,相当于轧制形状因子0.1630.对双金属条进行均匀化退火,于400℃保温不同时间.利使用扫描电子显微镜观察Al/Ag界面,研究可能存在的硬脆相.通过EDS分析和线扫描分析退火时间对扩散距离和相转变的影响.在界面上Ag侧观察到一个扩散区,其宽度随退火时间的延长而增加.退火处理3h后在靠近界面处观察到一些δ相,而且随着退火时间的延长,δ相变得更粗、更连续.显微硬度测试表明:尽管通过均匀化退火生成δ相,界面硬度却有所降低.%Aluminum and silver strips were cold welded by rolling and a bimetallic strip was produced.To create cold weld between Al and Ag,mating surfaces were specially prepared and various rolling thickness reductions were applied.The minimum critical thickness reduction to begin cold weld was specified as 70％ which equals 0.1630 critical rolling shape factors.The bimetallic strips were treated by diffusion annealing at 400 ℃ and various annealing time.The Al/Ag interface of strips was observed by scanning electron microscope to investigate the formation of hard and brittle probable phases.The effect of anneal time on diffusion distance and phase transformation was also analysed by EDS analysis and line scan.A diffusion region along the interface in the Ag side was observed and its width increased with prolonging annealing time.Some δ phases were detected close to the interface after anneal treating for 3 h and δ phase was thicker and more continuous by increasing annealing time.The microhardness measurement showed that in spite of formation ofδ phase due to diffusion annealing,the interface hardness was reduced.