The galvanized steels were joined using a TIG arc brazing process with CuSi3 as the filler metal. The arcing time ranged from 1 s to 5 s with arcing current of 70 A in flowing argon. The possible reaction products at the interface were confirmed using thermodynamics, SEM, and EDS methods. The results show that a fragmention behavior in some whisker-like intermetallic compounds happens, and that there are two layers of Fe2Si and Fe5Si3 formed at the interface of the galvanized steel and copper filler.From this, the schematic cycle of the interface growth behavior of Fe/Si compounds and the fragmentation behavior of whisker-like intermetallic compounds are developed.