Efficacy of an External Chromia Layer in Reducing Nitridation of High Temperature Alloys

Six high temperature alloys have been exposed in N 2 /H environments at 900 °C. In order to study the efficacy of a chromia barrier layer against nitrogen ingress, experiments were performed two having same ratio but slightly different water content, formation being spontaneous one case only. The samples evaluated by SEM/STEM/EDX, XRD, gravimetry and GD-OES. presence an external scale reduced nitridation alloy 50–95%. Furthermore, continuous alumina no was detected. • Nitridation 50–95% layer. An without macro defects proved prevent any detectable nitridation. resistance increased with concentration nickel alloy.