Stress release in α-Cr2O3 oxide thin films formed on Ni30-Cr and Fe47-Cr alloys
Résumé
For high temperature materials such as metallic Fe-Cr and Ni-Cr alloys, the oxide film which develops at the sample surface during annealing acts as a protective barrier. However, its mechanical integrity may be affected by strong compressive residual stresses which appear during the thin film growth and cooling processes. This paper reports a detailed study of the physical mechanisms responsible of the subsequent stress relaxation. For that purpose, nondestructive and destructive processes and their combination are carefully analyzed. A noticeable difference is found between the two alloys, grain boundary sliding and delamination mechanisms being dominant physical mechanisms for the Ni-30Cr alloy while a third phenomenon is clearly evidenced for the Fe-47Cr alloy. © 2017 Elsevier B.V.