A process for the passivation of crystal defects or grain boundaries or internal grain defects or surfaces in an electrically conductive material in a plasma, where the passivation is carried out by the influence of suitable ions on the electrically conductive material to facilitate a shorter process time and lower stress on the electrically conductive material. A high-frequency gas discharge plasma is acted upon by a superimposed d.c. voltage which serves to accelerate the ions, suitable to carry out the passivation, towards the electrically conductive material.