matched to the area to be treated the speed and the regeneration of the halogenated carrier can be controlled by an appropriate choice of the electrolytic deposits made on the wire it is not necessary to add any specific halogenated carrier to the channels since the halogenated carrier that exists in the treatment pack or in the vapor deposition treatment can penetrate by gaseous diffusion into the cavity to be treated and can find in situ the regeneration elements required to obtain the desired thermochemical equilibrium with the above mentioned part the channel having a diameter of 1 5 mm and a length of 250 mm was treated by using a pack having the following composition the donor piece 6 was constituted by a wire made of pure aluminum having a diameter of 0 4 mm and coated with 5 microns of nickel in this way a layer was formed inside the channel that had the same characteristics as the layer which was formed on the outside surface of the part to be treated aluminum content 28 to 35 over 50 of the thickness of the layer in conclusion the present invention makes it possible in particular to enrich various alloys with aluminum by thermochemical treatment inside very long channels into which it is difficult to penetrate the aluminum is supplied in the form of wires or strips made of pure or slightly alloyed aluminum and pre coated with nickel nickel and chromium cobalt or cobalt and chromium the quantity of aluminum inserted into the channel is controlled by the choice of the cross section of the aluminum wire or strip the activity i e the regeneration.