Microstructural changes in alloy 625 during high temperature creep

Microstructural changes in the nickel-base alloy G25 during creep deformation have been investigated in the temperature range of 923 to 1148 K for durations from 30 to 31,800 h. intermetallic phases such as gamma ''-phase and delta-phase have been found to precipitate extensively within the austenitic matrix under most of the test conditions. The gamma ''-phase was observed at 973 K and delta-phase was observed at all temperatures above 973 K. The morphology of the needle-shaped delta-phase was influenced by time and temperature of exposure and stress. An almost continuous decoration Of M23C6 type carbides was observed on the grain boundaries. (C) 2007 Elsevier Inc. All rights reserved.