Experimental investigation on interface phenomena involving spreading of Fe–Cr based filler metal

Abstract

Fe–Cr based alloy emerges as an economic alternative to Ni based filler metal applied in brazing of steels and high temperature alloys; however, its spreadability and interface microstructure have been very poorly studied. In the present study, wettability and interface microstructure of new type Fe–Cr–Ni–Cu–P–Si filler metal are investigated at different pressures. The molten Fe–Cr–Ni–Cu–P–Si filler metal demonstrated good spreadability both in vacuum and in air. Fingering phenomenon at the spreading edge indicated the dissolution of base metal during spreading and insufficient diffusion. Reactions promoted the fragmentation and removal of the oxide film, and the dissolution of oxide and base metal further improved the spreadability. These mechanisms indicate potential for an excellent brazeability of Fe–Cr–Ni-Cu–P–Si filler metal.