High-vacuum brazing of Mg-bearing aluminum alloys.

Vacuum brazability of aluminum alloys containing magnesium more than 1 mass% has been reported to be very poor. This study was aimed to examine brazability of those alloys in a high vacuum atmosphere of the order of 10−5 Pa. A6061, A5052 and A5083 alloy sheets with BAS211P brazing sheets were high vacuum brazed into invers T-type specimens. All of these alloys exhibited fairly good fillets. Spread of the brazing alloy on the surfaces of the brazed alloys and erosion of the brazing alloy into the brazed alloys were both limited in the high vacuum brazing. The behavior of magnesium during brazing is discussed, based on the results of EPMA analysis.