Abstract: Method and apparatus for introducing normally solid metals or metalloids into electrically conductive substrates. The invention is particularly useful in surface alloying of metal substrates and makes it possible to introduce metals into ferrous metal substrates to depths of 200 microns and more. The metal or metalloid to be introduced is maintained at an elevated temperature below the boiling point, the surface portion of the substrate is maintained at an elevated temperature below the deformation point, and a double glow discharge is employed under controlled conditions to transfer the metal or metalloid to the substrate.