Influence of interfacial dislocation network on strain-rate sensitivity in Ni-based single crystal superalloys

Abstract

The excellent mechanical properties of Ni-based superalloys rely on their unique two-phase microstructure. Here we probe the influence of interfacial dislocation network on strain-rate sensitivity in Ni-based single crystal superalloys. The interfacial dislocation could generate a weak long-range interaction to the matrix dislocations at low stress, and react with the incoming dislocation to form junctions at high stress. The weak interaction results in the dislocation pile-up around the interphase boundary, while the strong dislocation reaction makes the gradual loss of interface coherency. With the activation energies, we predict the dependence of strain-rate sensitivity on temperature in a regime with two bounds correlated with these two kinds of interactions. The predicted values match well with that measured in experiments at elevated temperatures.