Research on the Microstructure and Phase of Interface of Al Ion Implanted Stainless Steel/Al Joints

The brazing quality of stainless steel/Al was optimized by Al ion implantation pretreatment, and then the effect of brazing parameters on the microstructures and phases of the brazing joints were investigated. As Al ion is implanted into stainless steel for pretreatment, better stainless steel/Al brazing joint can be obtained. With the increase of brazing temperature and brazing time, the thickness of Al-Fe intermetallic compounds increases. The fracture mode of the stainless steel/Al brazing joints is closely related with the thickness of Al-Fe intermetallic compounds. As the thickness of Al-Fe intermetallic compounds are less than 10 mu m, the content of Al phase is very high at the fracture area by the stainless steel side, and the brazing joints failure at the brazing alloy area and ductile fracture occurs. As the thickness of Al-Fe intermetallic compounds are greater than 10 mu m, the content of Al-Fe intermetallic compounds such as Fe13Al4 and FeAl2 is very high at the fracture area by the stainless steel side, and the brazing joints failure at the intermetallic compound area and brittle fracture occurs.