ƒÁ/ƒÁ' Microstructural Changes Induced by Monotonic and Cyclic Loadings in a Single Crystal Ni-Base Superalloy
Motoki SAKAGUCHI, Hideaki TAKASHIMA, Hiroaki HAYASHI and Masakazu OKAZAKI
Abstract:This paper focused on microstructural changes in a single crystal Ni-base superalloy, CMSX-4, induced by external loadings. It was shown by a series of experiments that an application of the monotonic straining at R.T. and the subsequent heat treatment at high temperature resulted in a directional coarsening of ƒÁ/ƒÁ' microstructure, similar to "rafted structure" by creep. A critical strain was found to be needed to build up the microstructural change. The coarsening directions were significantly depending on the histories of straining. Not only monotonic but also cyclic loadings at R.T. and elevated temperatures could induce the similar changes in microstructure. These series of experimental works provide us a new method for failure and damage analysis of superalloy components. Key Words:Single crystal Ni-base superalloy, ƒÁ/ƒÁ' microstructures, Rafting, Monotonic loading, Cyclic loading, Intercept method, Damage detection