NOVELTY - The process comprises thermally treating a first sheet made of an aluminum of a metal assembly by heating the sheet to a temperature of 80-100 degrees C of melting temperature of constituent material to create and stabilize alpha alumina layer by allotropic transformation of an oxide layer present on a surface of the sheet and then cooling, providing a second metal sheet (20) of the metal assembly having a ductility that is less than or equal to a ductility of the sheet after cooling, and heating the second metal sheet at a temperature of 70-98 degrees C.    USE - The process is useful for fabricating an aluminum metal assembly, which is useful for manufacturing electrodes of fuel cell.    ADVANTAGE - The process is capable of rapidly, easily, economically and energy-efficiently fabricating the aluminum metal assembly with high tensile strength, rigidity and quality, good corrosion resistance, conductivity and mechanical properties and light weight.    DETAILED DESCRIPTION - The process comprises thermally treating a first sheet made of an aluminum of a metal assembly by heating the sheet to a temperature of 80-100 degrees C of melting temperature of constituent material to create and stabilize alpha alumina layer by allotropic transformation of an oxide layer present on a surface of the sheet and then cooling, providing a second metal sheet (20) of the metal assembly having a ductility that is less than or equal to a ductility of the sheet after cooling, heating the second metal sheet at a temperature of 70-98 degrees C of the melting temperature of the metal for a determined duration according to the thickness of the sheet, cooling the sheet to room temperature, assembling the aluminum sheet (10) and the second metal sheet by riveting, welding, pre-rolling of a head of the sheets, self tapping screws, electron beam welding, bonding and/or clamping, applying a powder layer on the aluminum sheet, and cold roll bonding the aluminum sheet and the metal sheet in a rolling mill to produce the metal assembly. The second metal sheet has surface irregularities of depth greater than or equal to a thickness of the alpha alumina layer. The mill comprises a smooth cylinder of which an outer rolling surface is provided with raised portions such as straight, toothed, notched and/or sinuous grooves or cross. A duration of the thermal treatment is 20 minutes to 2 hours. The raised portions extend in a direction parallel and/or transverse to the rolling direction of sheets in the rolling mill. The outer rolling surface of the cylinder has identical raised portions that are oppositely faced during roll bonding. The second metal sheet is constituted of metal grid, foam, metallic honeycomb structure, cables, and rough metal sheet. The second metal sheet is stripped between the cooling and roll bonding steps, and receives a surface treatment. The aluminum sheet and powder are roll bonded in the smooth cylinder to obtain an assembly plane, which is then roll bonded with the second metal sheet in the rolling mill to obtain the metal assembly. The metal powder is dried prior to its application on the aluminum sheet. An INDEPENDENT CLAIM is included for a process for fabricating a heat exchanger.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a metal assembly.    Aluminum sheet (10)    Second metal sheet (20)    Metal tubes. (30)