High Temperature Creep Behavior and Fracture Characteristics of a 2%Ru Nickel Based Single Crystal Superalloy

The creep behavior and fracture characteristics of a new type of 2%Ru nickel base single crystal superalloy was studied through measurement of creep properties and microstructure observation. The results show that the alloy has good creep properties at 1070–1100 °C and 127–147 MPa. The apparent activation energy of creep is: Q = 416.8 kJ/mol and the stress index n is: n = 4.67 at the steady creep stage. The deformation mechanism of alloy in the steady state of creep is that the dislocation slip in the matrix and climb over the γ′ phase in the matrix, and the dislocation can be cut into the γ′ phase in the late stage of creep. Under high temperature and low stress, the γ′ phase of the alloy can form raft structure, and the crack initiation at the interface between the raft γ′ phase and the matrix phase. With the crack propagation, aggregation and connectivity, the creep resistance of the alloy decreases sharply, which eventually leads to creep rupture of the alloy.