Abstract
Interfacial fatigue crack propagation along the Mar-M247 Ni-based superalloy/CoNiCrAlY alloy coating film was studied at 873 K, and the effect of loading mode was discussed. At first the crack propagation resistance was clarified under Mode I loading, influenced by the substrate surface roughness. Next, efforts was made to understand the naturally initiated interfacial small crack propagation behavior under the Mode II dominant loading condition, in which the cyclic axial load was applied parallel to the interface. The interfacial crack was found to reveal a noteworthy behavior the growth rate proportionally increased with the interfacial crack length just after the crack initiation, then decreased and finally arrested.
