Al/Mg扩散层的形成规律和机理

Forming rule and mechanism of Al/Mg diffusion layer

采用镶嵌式扩散偶,在不同退火热处理条件下,对Al/Mg扩散层进行了研究.利用扫描电子显微镜和电子探针观察和分析了扩散层的形态和结构,从扩散、溶解与结晶角度探讨了扩散层的形成机理.结果表明,当580℃保温60 h退火处理后,在Al/Mg界面处形成了厚度约265μm、结构为Al/Mg2Al3/MgAl/Mg3Al2/Mg的扩散层,其结构相与Al-Mg相图上相的排列位置一致.在不同的扩散温度和时间下,Al/Mg相界面处将几乎同时结晶出不同层数、厚度和结构的扩散层;扩散层的形成是Al和Mg固相扩散、溶解与结晶的结果.

By using diffusion couple made by inlaying,the diffusion layer of Al/Mg was researched under different anneal condition.The microstructure and forming rule were observed and analyzed by means of scanning electron microscopy(SEM) and Energy Disperse Spectroscopy(EDS),and its forming mechanism was discussed.The results showed that the diffusion layer was formed at Al/Mg interphase with heating temperature of 580 ℃and holding time of 60 hours,its thickness was 265 μm,its structure was Al/ Mg2Al3/ MgAl/Mg3Al2/Mg,which included all phases in Al/Mg binary alloy phase diagram,and the structure was consistent with the sequence of each phase located Al/Mg phase diagram.The solid phase diffusion,dissolve and crystal of Al and Mg resulted in forming of diffusion layer with different diffusion temperature and time,and the diffusion layer was almost formed at Al/Mg interphace at the same time,which was different number of layer,thickness and structure.