The invention discloses a vacuum
brazing device which improves the
brazing performance and quality of an aluminum and aluminum
alloy workpiece and a method using the device to braze an aluminum
alloy workpiece. The vacuum
brazing device comprises a
magnesium vapor generating chamber, a brazing chamber and a
magnesium collecting chamber, wherein the
magnesium vapor generating chamber, the brazing chamber and the magnesium collecting chamber are hermetically communicated with each other through a
pipe; and the magnesium vapor generating chamber is internally provided with an
electric heating device and the magnesium collecting chamber is internally provided with a collecting
copper net with a cooling water pipeline. During brazing, pure magnesium is placed on the
electric heating device, the workpiece and the brazing
filler metal are placed in the brazing chamber, and then the vacuum brazing device is placed into a vacuum brazing furnace integrally; the
oxide film on the surface of the aluminum
alloy workpiece is thoroughly removed by flow of magnesium vapor according to different vapor pressures of magnesium in the three chambers, so that the brazing deficiencies such as crack,
oxide inclusion, insufficient brazing and non-brazing and the like in the brazing position of the aluminum alloy workpiece in a complex structure can be strictly controlled, thereby, improving the brazing performance and quality of the aluminum alloy brazing workpiece to a great extent.