MODIFICATION OF STEEL SURFACES FOLLOWING PLASMA AND ION BEAM IMPLANTATION INVESTIGATED BY MEANS OF CEMS

摘要

The Moessbauer and tribological investigations of the surface of high-speed M2 steel after different kinds of implantation allow us to conclude that the methods of high-current, plasma-immersion implantation and CPF lead to the formation of a multi-layer multiphase system, which enhances the mechanical properties of steel. After high-current implantation with nitrogen and boron the formation of thin surface layers with nitrides α"-Fe_(16)N_2, ε-Fe_xN and borides FeB, Fe_2B takes place, and the formation of a layer with a thickness up to 10 μm containing only nitrides. In addition, high-current implantation leads to some ordering of the martensite structure. A presence of double-layer system with borides and nitrides increases the micro hardness of surface and decreases the friction coefficient by approximately two-fold. Plasma-immersion implantation leads to the formation of S-phase (expanded austenite) in a thin surface layer of about 0.1μm, that enhances the mechanical properties of steel. CPF treatment creates a double layer system with increased microhardness and decreased friction coefficient.