Snoek-Dominated Internal Friction Response in bcc Steel: Relating Experiments With a Multi-scale Atomistic Computational Framework

S Manda and S Kumar and K Pal and AR Bhattacharyya and AS Panwar and I Samajdar, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 54, 562-576 (2023).

DOI: 10.1007/s11661-022-06899-5

Internal friction is often sensitive to microstructural features. However, there is a clear absence of rational approach for decoupling internal friction spectra for diverse microstructural inputs. In this study, a robust multi-scale atomistic computational framework, combining atomistic kinetic Monte Carlo and molecular dynamics simulations, has been proposed. Predictions from our simulations were then compared with careful experiments on engineered microstructures in bcc steel. Specifically, theoretical contributions from interstitial solute type and concentration, crystallographic orientation, and residual stress (RS), were compared to actual experimental results. The atomistic computational framework successfully demonstrated that the overall internal friction response was composed, almost entirely, of Snoek relaxations from interstitial atoms. Ideal single-crystal simulations correctly predicted peak dissipation temperatures and Snoek peak height, tan delta(max), when compared with available single-crystal experimental data. The simulations also captured the correct experimental trends with residual stress and crystallographic orientation in polycrystalline bcc steel. In particular, both RS and crystallographic orientation affected internal friction response by altering diffusion barriers for interstitial migration. Our study, thus, established that an integrated computational framework, supported with careful experiments, can be extremely effective in decoupling various microstructural inputs to complex experimental internal friction spectrum.

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