|About this Abstract
||MS&T23: Materials Science & Technology
||Integration between Modeling and Experiments for Crystalline Metals: From Atomistic to Macroscopic Scales V
||From Anti-Arrhenius to Arrhenius Behavior in a Dislocation-obstacle Bypass
||Mohammad Nahavandian, Enrique Martinez Saez, Soumit Sarkar
|On-Site Speaker (Planned)
Dislocations are the primary carriers of plasticity in metallic material. Understanding the basic mechanisms for dislocation movement is hence paramount to predicting the material mechanical response. Relying on atomistic simulations, we observe a transition from anti-Arrhenius to Arrhenius behavior in the rate for an edge dislocation to overcome the elastic interaction with a prismatic loop in tungsten. Beyond the critical resolved shear stress, the dislocation shows an anti-Arrhenius behavior at low temperatures. However, as the temperature increases, the activation entropy starts to dominate, leading to a traditional Arrhenius behavior. We have computed the activation entropy analytically along the minimum energy path following Schoeck’s expression, matching the results from molecular dynamics simulations well. We conclude that entropic effects need to be considered to obtain a complete understanding of processes involving dislocations bypassing elastic barriers.