The invention is related to a surface treatment method employing electrical discharges, of which the parameters are chosen so as to minimize the removal of material and to counteract the phenomenon of localization, discharges which strike in an intermediate space between a tool-electrode and a part-electrode, or gap, filled with a dielectric liquid and enabling defects to be eliminated associated with the residual white layer produced by electrical discharge machining during resolidification of part of the material melted by the erosive sparks and to obtain, at the surface of part-electrode, a non-crystalline amorphous structure that can replace all or part of said white layer,
said method being characterized by the use of two types of powder,
the first type consisting of nanometric sized particles,
the second type consisting of micrometric sized particles,
and the size distributions of the particles of the first and second types being different.