Investigations on the Growth Mechanisms of α‐Cr2O3 on Ni‐Base Alloys with and without Y2O3 Dispersions

Publisher Website
Google Scholar
Abstract
The growth kinetics of Cr2O3 scales on the Y2O3 dispersion containing Ni‐base alloy MA754 at low oxygen partial pressure have been compared with the corresponding growth rates on Ni‐30Cr and on Ni‐30 Cr‐0.5 Ti alloys in the 1000–1125°C temperature range. In the dispersion containing alloy, the growth kinetics are slower by a factor of 12–14, the Ni‐30 Cr and Ni‐30 Cr‐0. 5 Ti alloys exhibiting similar growth rates. Microstructural evidence does not support mechanisms for growth rate reduction suggested by earlier investigators based on blocking effects of dispersoid particles or dispersoid‐assisted generation of a fine‐grained Cr2O3 scale. Rather, the present evidence supports a model based on yttrium doping. It is shown that in undoped Cr2O3 at low oxygen partial pressures, chromium interstitials are the most probable cationic defects, yttrium doping suppresses the concentration of chromium interstitials.

This publication has 8 references indexed in Scilit: