The unique failure behavior of Ni-Mo-Cr-Gd superalloy during hot compression at ultrahigh temperatures

The unique failure behavior of the Ni-Mo-Cr-Gd superalloy deformed at 0.01 s-1 and 0.5 strain with ultra-high temperatures has been investigated. The samples compressed at 0.01 s-1 and 0.5 strain are severely cracked at 1230 degrees C, and almost completely crushed at 1250 degrees C. The microstructure observations show that the divorced gamma/Ni5Gd eutectic phase transforms into the lamellar gamma/Ni5Gd eutectic phase, and the Ni5Gd phase disappears in the center of samples, especially at 1250 degrees C. Here, the eutectic transformation is attributed to the fact that the Ni5Gd phase melts and solidifies due to the temperature rise of local interface friction between the Ni5Gd phase and the gamma matrix. Furthermore, the severe failure of samples and the unexpected disappearance of the Ni5Gd phases were ascribed to the interconnected localized melting regions of the Ni5Gd phase.