Abstract: A joined part of an aluminum-coated steel sheet and an aluminum sheet is composed of an intermetallic compound layer which exists in a region in which a part of a coated layer exists before the joining and an aluminum melted and solidified part which also exists on the side of the aluminum sheet to enclose the intermetallic compound layer. The atoms existing on the surface of the aluminum melted and solidified part are intermetallic-bonded with atoms which exist on the surface of the steel sheet except in the region in which the intermetallic compound layer exists seen in the plan view. Further, the area of the intermetallic compound layer is limited to 60% or less of the total area of the joined part at the interface between the aluminum-coated steel sheet and the aluminum sheet. Thus, the area of the aluminum melted and solidified part exceeds 40% of the total area of the joined part. The strong joining having a high fracture energy can be provided at a high efficiency.

Abstract: A core material of an aluminum brazing sheet restricts Mg to less than 0.3 wt % and Fe to not more than 0.2 wt %, and contains more than 0.2 wt % and not more than 1.0 wt % of Cu, 0.3 to 1.3 wt % of Si, 0.3 to 1.5 wt % of Mn and the balance of Al and inevitable impurities. A brazing filler material is formed on one surface of the core material by Al—Si based aluminum alloy. Also, a cladding material is formed on the other surface of the core material, and contains less than 0.2 wt % of Si, 2.0 to 3.5 wt % of Mg, not less than 0.5 wt % and less than 2.0 wt % of Zn and the balance of Al and inevitable impurities. Further, the value (cladding material hardness)/(the core material hardness) that is a ratio of the hardness of the cladding material to the hardness of the core material is not more than 1.5.

Abstract: A core material of an aluminum brazing sheet restricts Mg to less than 0.3 wt. % and Fe to not more than 0.2 wt. %, and contains more than 0.2 wt. % and not more than 1.0 wt. % of Cu, 0.3 to 1.3 wt. % of Si, 0.3 to 1.5 wt. % of Mn and the balance of Al and inevitable impurities. A brazing filler material is formed on one surface of the core material by Al-Si based aluminum alloy. Also, a cladding material is formed on the other surface of the core material, and contains less than 0.2 wt. % of Si, 2.0 to 3.5 wt. % of Mg, not less than 0.5 wt. % and less than 2.0 wt. % of Zn and the balance of Al and inevitable impurities. Further, the value (cladding material hardness)/(the core material hardness) that is a ratio of the hardness of the cladding material to the hardness of the core material is not more than 1.5.

Abstract: A zincate-treated article of an Al-Mg-Si base alloy has a zincate coating film having a Zn crystal grain size of 1.0 .mu.m or smaller on an Al-Mg-Si base alloy body having a Cu content of 0.1 to 1.5 weight %. The Zn crystal grain size is preferably equal to or smaller than 0.95 .mu.m. This zincate-treated article can be manufactured by treating an Al-Mg-Si base alloy body having a Cu content of 0.1 to 1.5 weight % in a zincating treatment bath containing 100 to 300 g/l of sodium hydroxide, 5 to 20 g/l of zinc oxide, 2 to 10 g/l of iron chloride, 5 to 20 g/l of Rochelle salt and 50 to 200 ml/l of water glass at a temperature of 20.degree. to 80.degree. C. for 5 to 60 seconds. By adjusting the Zn crystal grain size in the zincating treatment in this manner, a zincate-treated article of an Al-Mg-Si base alloy having an excellent adhesion can be acquired even in a single stage zincating treatment.

Abstract: An aluminum alloy composite material for brazing has a core member, an Al--Si filler member clad on one surface of the core member and an aluminum alloy cladding member clad on the other side of the core member. The core member is made of an aluminum alloy containing 0.3 to 1.3 wt. % of Si, 0.3 to 1.5 wt. % of Mn, 0.02 to 0.3 wt. % of Ti, and, as required, 0.3 wt. % or less of Cr and 0.2 wt. % or less of Zr, the content of Mg being restricted to 0.2 wt. % or less and the content of the Cu being restricted to 0.2 wt. % or less as an impurity. The cladding member is made of an aluminum alloy containing 0.3 to 3 wt. % of Mg, 5 wt. % or less of Zn, 0.1 to 1.0 wt. % of Si. The thickness of the core member is preferably, 2.5 times or more greater than that of the filler member, falling within a range of 0.1 to 1 mm.