Creep and damage of a Re/Ru-containing single crystal nickel-based alloy at high temperature

Abstract

Abstract By means of creep property measurement and microstructure observation, combined with finite element analysis (FEA), the creep and damage of a 4.5%Re and 3%Ru single crystal nickel-based alloy at high temperature were investigated. The results show that the creep life of the single crystal alloy at 1100\xa0°C/140\xa0MPa is 476\xa0h. The deformation feature of alloy during steady state creep is dislocation slipping in γ phase and climbing over γ′ rafts. The various stress distributions are displayed in the different regions of sample during creep. As the creep goes on, the stress value in the gauge region of sample may increase to a value being bigger than the yield strength, which may cause the plastic deformation of local region in alloy. In the late creep period, the deformation feature of alloy is dislocations shearing γ′ rafts, and the dislocations of shearing γ′ rafts may cross-slip to form the K–W locks. Moreover, the alternated slipping of dislocations can both twist γ/γ′ rafts and rotate γ′ crystal to form the sub-grain structure, which may reduce the resistance of alloy. Wherein, the twisted γ′ rafts with weaker strength, due to the shearing of dislocations in the late period of creep, is reversely transformed into the block-like configuration, which weakens the resistance of alloy. While the cause of the life being decreased at 1140\xa0°C to a great extent is attributed to the γ′ phase being dissolved to diminish its size and volume fraction.