Modeling Plasticity of Ni3Al-Based L12 Intermetallic Single Crystals-I. Anomalous Temperature Dependence of the Flow Behavior (Preprint)

摘要

A comprehensive mechanism-based crystallographic constitutive model has been developed for L 12-structured Ni3Al-based intermetallic single crystals. This model represents the unusual thermo-mechanical behaviors of Ni3Al, such as the anomalous temperature dependence of both the flow stress and strain-hardening rate (SHR), the strain dependence of these anomalous behaviors, and an orientation-dependent tension-compression asymmetry. The model framework was based on two major contributions to plastic flow, namely the repeated cross- slip exhaustion and athermal defeat of screw-character dislocations, and the motion of the macro-kinks (MKs). The contribution of irreversible obstacle storage was incorporated into the constitutive formulations as a resistance against the glide of MKs. The model was implemented in a finite element method numerical framework, and the simulation results showed qualitative agreement with experimental observations.