Creep Deformation Property of MCrAlY Bond Coatings by High-Temperature Creep Indentation Tests

In this study, the creep constants involved in the creep constitutive equation of MCrAlY bond coatings were identified using a high-temperature creep indentation test developed by our group. CoNi, Co, and Ni were selected as M components. The effects of the M components and spraying processes of atmospheric plasma spraying (APS) and high-velocity flame spraying (HVOF) on the creep constants were also investigated. As a result, the creep exponent \(n\) was in the range of 6-8, regardless of the difference in the M components and thermal spraying processes. On the other hand, the creep coefficient \(k\) was the largest in CoNiCrAlY (HVOF), and it was clear that it has the capability of large stress relaxation owing to creep deformation between the ceramic top coating and substrate. SEM observations revealed that the dispersed phase in the matrix was lost with increasing temperature, which led to a reduction in dislocation obstacles and an increase in creep deformation in the CoNiCrAlY bond coatings.