From anti-Arrhenius to Arrhenius behavior in a dislocation-obstacle bypass: Atomistic simulations and theoretical investigation

Journal Article · 28 March 2024 · Computational Materials Science

DOI: https://doi.org/10.1016/j.commatsci.2024.112954 · OSTI ID:2563363

Nahavandian, Mohammadhossein  ^[1]; Sarkar, Soumit ^[1]; Bagchi, Soumendu  ^[2]; Perez, Danny  ^[2]; Martinez, Enrique  ^[1]

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1. Clemson University, SC (United States)
2. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Dislocations are the primary carriers of plasticity in metallic materials. Understanding the basic mechanisms for dislocation movement is paramount to predicting the material mechanical response. Relying on atomistic simulations, we observe a transition from non-Arrhenius to Arrhenius behavior in the rate of an edge dislocation overcoming the long-range elastic interaction with a prismatic loop in tungsten. Close to the critical resolved shear stress, the process shows a non-Arrhenius behavior at low temperatures. However, as the temperature increases, the activation entropy starts to dominate, leading to a traditional Arrhenius-like behavior. Here, we have computed the activation entropy analytically along the minimum energy path following Schoeck’s method, which captures the cross-over between anti-Arrhenius and Arrhenius domains. Also, the Projected Average Force Integrator (PAFI), another simulation method to compute free energies along an initial transition path, exhibits considerable concurrence with Schoeck’s formalism. We conclude that entropic effects need to be considered to understand processes involving dislocations bypassing elastic barriers close to the critical resolved shear stress. More work needs to be performed to fully understand the discrepancies between Schoeck’s and PAFI compared to molecular dynamics.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR). Scientific Discovery through Advanced Computing (SciDAC); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: 89233218CNA000001; SC0008875
• OSTI ID: 2563363
• Alternate ID(s): OSTI ID: 2329532
• Report Number(s): LA-UR-25-23415
• Journal Information: Computational Materials Science, Vol. 239; ISSN 0927-0256
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English