Brazing is the process in which two metals are joined by a filler metal, which is melted and poured into the joint.  Brazing is similar to soldering but is done at a higher temperature.  It differs from welding in that the work pieces are not melted. 

Due to capillary action, the molten metal is able to flow into even minute gaps in the joint.  Brazing can result in joints, which have good strength. 

To prevent the formation of oxides when the material is heated, a layer of flux, such as borax is applied over the metal which is heated.  The type of flux depends on the base metals and the filler metals used for the joint.