The spreading behaviour of Cu, CuSi, CuMnNi, and TiCuNi ller metals with Ti6Al4V titanium alloy base metal has been studied under gas tungsten arc welding heating. Test results showed that the wet angle of CuMnNi ller metal was the smallest (15°) and that of Cu was the largest (30°). With spreading, the liquid ller metal solidi ed and crystallised simultaneously, and formed a spherical crown brazing seam. The wettability and spreadability of the liquid ller metal were related to oxide scale actions with arc heating. These actions included the 'cleaning action of the cathode' and lashing activation action of electrifying ions and electrons. Furthermore, the very high temperature of the activation spot zone partly melted the base metal surface and near surface metal, and a thin liquid lm was accordingly formed that created a strong heating activation. It was also discovered that there was a column solid -liquid incongruent compound g(MeTi 2 ) at the interface of ller metal and base metal (MezCu, CuzNi, CuzMn). This compound grew to form an interface with the centre of the brazing seam and was embedded in it. The particular crystallising and growing mode in the arc heating helped grow the column solid -liquid incongruent compound g(MeTi 2 ).MST/5668

Galvanised steels have been joined using an arc brazing process with Cu 97 Si 3 as the filler metal. The arcing time ranged from 1 s to 5 s with arcing current of 70 A in flowing argon. Excellent wetting between the base materials and the filler was observed for all samples. The reaction and products were confirmed by analysis of possible reaction products at the interface using thermodynamics, SEM, and EDS methods. From this, the schematic cycle of the interface Fe/Si compound growth mechanisms and fragmentation mechanisms of a whiskerlike intermetallic compound were determined. It has also been observed that Fe 5 Si 3 (Cu) particles are most likely to be generated at the interface through 'dissolve separation' 'whiskerlike compound fragmentation', and 'anode spot action' methods in the present arc brazing process.