Rapid Cooling And The Diffusion Behavior Of Si Element In The Sample Of The General Of Al-si Brazing

The ribbons of Al-Si alloy have been made out by rapid solidification method. The melting point and the component of the ribbons are measured with X-ray diffraction, EDS and DTA separately. Then the diffuse behavior of Si element is observed with the EDS .The differences of the diffuse ability of Si between the as-cast and rapid solidification Al-Si brazing metal are preliminary investigated and discussed .The results indicated that the diffuse behavior of Si element in matrix is basically same , no matter what it came from rapid solidification or as-cast brazing metal .The diffuse speed and depth of Si element in rapid solidification brazing metal are higher than that in as-cast one . Because the grains of rapid solidification brazing metal are fine and there is more Si element distributes on the grain boundary , a 'liquid phase channel' is formed . So the diffuse speed of Si element in rapid solidification brazing sample is faster.The author further researches and explores the different diffuse action of element Si in liquid and solid zone .The results indicated that the element Si diffuse toward the substrate driven by the concentration grads in the initial stages of melting.The components with low melting point flow toward the substrate and the phase with high melting point deposit gradually and then form the "remnant brazing metal layer".The element Si diffuses along the grain boundary of the substrate in depth direction and present an obvious linear distributing state with the increasing of the diffusion depth.