Mass-transport driven by surface instabilities under high-flux, low-energy nitrogen ion irradiation at elevated temperatures

Flux effects in ion nitrided AISI 304 stainless steel have been investigated in an attempt to understand the mechanism of nitrogen transport. It is concluded that an interaction between a highly activated surface layer, the internal interfaces and the bulk is critical. Under conditions of non-equilibrium present on the surface, the nitrogen atoms are driven into the grain boundaries and highly compressive stress is formed. The stress relaxation processes initiate plastic flow of atoms in the grains and a corresponding flow of nitrogen atoms. (C) 2003 Elsevier Ltd. All rights reserved.