The effect on dissolution and passivation of ion implantation of nitrogen and molybdenum in austenitic stainless steels

WS and elmtroch&cal analpis bve been used to investigate the influeme of Mo 8nd N implantation on disol~tionan d plvati6no f384 type M e s ss teel. The samples were implanted erst with MO ions and thar with N ions (2.52016 N and 2.5 1016 Mo at.cm2). Prior to the electmhmical exprhents, w- with we1 Mined Mo and N ecncentntions were pr&ced by argon ion sputtering the implmtd alloy for a fixed tjme in the pfep~atim chamber of the ~ywtrmeterh order to reach a weU-d&ed pint on the Mo and N depth profiles. Three.rcgions of the implar~tafionp rQfiles( hi@ Mo-high N concentration, medium Mo-high N cancsntration and low Momdim N mmxntration) were investigated. Far cash region the mptes were trai~sfmd without air exposure from the qwirorneta to an elearnchemical d l rncmtnred in an inert gas glove box. The ivlo-N cc-imphhtim modifies the cltxtrod~emid behaviour of h e alloy in 0.5M %SO4 sc~hrtion. The anodic dissqhtion mmt density increases with deacasicg Mo wcceimrat ionat the ~ukace md with increasing N ,concentration. SurFace andysis by W S &r pawivstion shows t bat co-implanted N &d Mo (in the Moechendcd state ) m enriched on the surfwe during dis~dution d.pam ivation of the alloy. The passive films form& on the a~hpIantedd loy have a bdayer structure with asp inner oxide layer and outer hydroxide layer. The presence ofMo and N favors the formation of Cr hydmxyde and Cr nitride.