A method is disclosed for brazing without filler metal two components, of which at least one is an Al alloy. According to the method, prior to brazing, at least one Al alloy component is maintained in a region of temperatures included between the temperature of solvus T.sub.v of the alloy and 2/5 of temperature of fusion (solidus) T.sub.s of the alloy, expressed in degrees Kelvin, for a sufficient period of time. After this treatment, which may or may not be isothermal, the alloy is suitable for brazing in a domain of temperatures included between the temperature of fusion T.sub.e of the most fusible eutectic corresponding to the equilibrium diagram of the constituents of the alloy, and that of the solidus of the alloy. The method permits the realization of perfectly homogeneous brazed seams for alloys considered not to be brazable.
The invention relates to a gastight connection between tubes of small diameter of metals or metal alloys having different melting points, more particularly copper and aluminium, wherein the end zone of the first tube (1) is opened out and the second tube (2) of a lower-melting material is inserted and soldered into the opened-out portion (3), the internal generated surface of the opened-out portion (3) merging via an internal cone (4) and extension (38) into that zone of the first tube (1) which is not opened out, a sleeve (34) of special steel possibly being inserted in the end zone of the second tube (2).
A novel method is described for joining aluminum surfaces by brazing. The method comprises (a) applying as a coating to at least one of the aluminum surfaces to be joined a mixture of a metal and a brazing flux, the metal of the mixture being adapted to form a brazable eutectic with the aluminum, (b) heating the surfaces and the coating in juxtaposed relation to a temperature above the brazing alloy melting point to thereby dissolve oxide film on the surface to be joined, cause the metal of the coating to dissolve into the oxide-free aluminum surface and form therewith a brazing alloy layer and form a brazed assembly and (c) cooling the brazed assembly to form a solidified joint between the surfaces. This has the advantage of providing for the joining of aluminum surfaces by brazing without the prior formation of a brazing alloy cladding on the surfaces to be brazed.
