In a brazing process, the composition and property of the brazed joint are greatly varied by metallurgical interaction of base metal and with filler metal and by flow of liquid filler metal. Therefore, it is important to elucidate the reaction between base metal and filler metal. In the basic reaction in brazing the followings may be considered: (1) Liquid filler metal dissolves base metal. (2) The filler metal diffuses into the base metal by inter-crystalline bulk diffusion or by intergranular penetration. (3) Intermetallic compounds are formed at the interface between base metal and filler metal. (4) The filler metal reacts on surface oxides of base metal to form slag products. Furthermore, there is still important problem that the structures of the solidified interface affects the properties of the brazed joints.
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