Constitutive Modeling for a Directionally Solidified Nickel-Based Superalloy

Alloy IC10, which is one of the newly developed nickel-base superalloys, has been applied in new generations of aero-engines. In order to investigate its flow behavior, tensile experiments were conducted over a wide range of temperatures (293 K similar to 973 K) and strain rates (10(-4)similar to 10(-2) s(-1)) on a material testing system (MTS809). The deformation mechanisms of IC10 were studied using transmission electron microscopy (TEM). TEM images showed that there were only screw dislocation segments locked by KW locks and connected by plenty of superkinks. In order to describe the mechanical properties of IC10, a mechanism-based constitutive model was developed by a homogenized approach. In this model, two assumptions are made: (1) the yielding and hardening behavior of IC10 are the net effects of point obstacles opposing the motion of dislocations; (2) the mobility of dislocation is connected to its superkink heights. Hence, the evolution of the mobile dislocation density can be developed on the basis of the evolution of whole dislocation density and the distribution of their superkink heights. The evolution of obstacle density can be derived from the evolution of the mobile dislocation density. At last, the model was successfully used to simulate the flow behavior of IC10 under different experimental conditions.