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Plastic Deformation of a Nano-Precipitate Strengthened Ni-Base Alloy Investigated by Complementary In Situ Neutron Diffraction Measurements and Molecular-Dynamics Simulations


  • EWH appreciates the financial support from National Science Council (NSC) 101-2221-E-008-039-MY3 Program. YLH thanks the NSC-99-3113-Y-042-001 Program. This research is also supported by the National Science Foundation (NSF) Programs (DMR-0231320, DMR-0909037, CMMI-0900271, and CMMI-1100080). TU is grateful to the Hungarian National Science Foundation OTKA #67692, #71594 and #83793 for supporting this work. The Los Alamos National Laboratory is operated by the Los Alamos National Security LLC under the DOE Contract of DE-AC52-06NA25396. The authors are grateful to the National Center for High-performance Computing for computer time and facilities.


In situ neutron-diffraction experiments at the spallation neutron source, simultaneously illuminating the diffraction of the matrix and the strengthening nano precipitates, allow the determination of their plastic deformation. An irreversible neutron-diffraction-profile evolution of the nano precipitates is observed. However, there is no conclusive trend of the nano-precipitate peak-width evolution subjected to the greater stress levels. Hence, in the present work, molecular-dynamics simulations are applied to reveal the deformation mechanisms of the nano precipitate and its interaction with the surrounding matrix. The microstructure size, dislocation content, and structural parameters of the nano precipitates, quantified by X-ray, transmission electron microscopy, and small-angle neutron scattering, are used as the simulation input and reference. The simulation results show that there are two competing deformation mechanisms, which lead to the fluctuation of the nano-precipitate-diffraction widths, occurring during the higher plastic deformation stages.