The soldering aluminum alloys containing high amounts of Mg with aid of ultrasonic vibration

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has been well known that the aluminum alloys containing a large amount of magnasium was impossible tobe soldered, so far. This study was carried out to make the soldering possible and to obtain the joints with higher sttrength introducing ultrasonic vibration into the soldered layrs.Since we have been successful in soldring the pure aluminum in atmosphere withou flux by using ultrasonic vibration, we tried to apply to the aluminum alloy containing magnasium difficult to be solderd with the aid of ultrasonic vibration. Using pure zinc metal, the joint of the tensile strength of approximately 160MPa was achieved. This strength is of about 50 % of a base metal, is not so sufficient. The detailed observation of soldered layr revealed that many Mg-inclusions ascribed to the dissolution of basemetal existed and the fracture path was along these inclusions, and it is expected that the formation of Mg-inclusions are the harmful factors to decrease the tensile strength of the joints.It was anal … More yzed with EPMA,AES and ESCA that magnasium was segregated onto the faying surface by heating, followed by causing the formation of the Mg-inclusions. Based on the analysis, the following countermeasure was adopted to increase the joint strength. That is, the heating rate was increased to suppress the magnesium segregation, and the filler metal of Zn-Al-Si alloy was used to decrease the dissolution of the base metal, and to increase the strength of a filler metal itself. As a result, the dissolution of the base matel was suppressed to some extent, but the joint tensile strength was insufficiently increrased.We selected again the pure zinc foil as a filler metal and examined the possibility to increase the joint tensile strenght through the grain refinement by solidifying structure control in addition to the suppression manganese segregation by rapid heating. These countermeasures increased successfully the joint tensile strength of the aluminum alloy containning Mg of 2.5% over the base metal strength.This new soldering method using ultrasonic vibration was applied to the commercially sized specimens. Unfortunately, the jointstrength was insufficient because the soldered area was of about 60% in the faying area due to the loss in transferring the ultrasonic vibration. Less