GeV ion irradiation of NiFe and NiCo: Insights from MD simulations and experiments

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http://hdl.handle.net/10138/313732

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Leino , A A , Samolyuk , G , Sachan , R , Granberg , F , Weber , W J , Bei , H , Lie , J , Zhai , P & Zhang , Y 2018 , ' GeV ion irradiation of NiFe and NiCo: Insights from MD simulations and experiments ' , Acta Materialia , vol. 151 , pp. 191-200 . https://doi.org/10.1016/j.actamat.2018.03.058

Title: GeV ion irradiation of NiFe and NiCo: Insights from MD simulations and experiments
Author: Leino, Aleksi A.; Samolyuk, German; Sachan, Ritesh; Granberg, Fredric; Weber, William J.; Bei, Hongbin; Lie, Jie; Zhai, Pengfei; Zhang, Yanwen
Contributor: University of Helsinki, Department of Physics
Date: 2018-06-01
Language: eng
Number of pages: 10
Belongs to series: Acta Materialia
ISSN: 1359-6454
URI: http://hdl.handle.net/10138/313732
Abstract: Concentrated solid solution alloys have attracted rapidly increasing attention due to their potential for designing materials with high tolerance to radiation damage. To tackle the effects of chemical complexity in defect dynamics and radiation response, we present a computational study on swift heavy ion induced effects in Ni and equiatomic Ni -based alloys (Ni50Fe50, Ni50Co50) using two-temperature molecular dynamics simulations (2T-MD). The electronic heat conductivity in the two-temperature equations is parameterized from the results of first principles electronic structure calculations. A bismuth ion (1.542 GeV) is selected and single impact simulations performed in each target. We study the heat flow in the electronic subsystem and show that alloying Ni with Co or Fe reduces the heat dissipation from the impact by the electronic subsystem. Simulation results suggest no melting or residual damage in pure Ni while a cylindrical region melts along the ion propagation path in the alloys. In Ni50Co50 the damage consists of a dislocation loop structure (d = 2 nm) and isolated point defects, while in Ni50Fe50, a defect cluster (d = 4 nm) along the ion path is, in addition, formed. The simulation results are supported by atomic-level structural and defect characterizations in bismuth-irradiated Ni and Ni50Fe50. The significance of the 2T-MD model is demonstrated by comparing the results to those obtained with an instantaneous energy deposition model without consideration of e-ph interactions in pure Ni and by showing that it leads to a different qualitative behavior.
Subject: Nickel alloys
Lattice
Defects
Scanning/transmission electron microscopy (STEM)
Molecular dynamics
EXCITATION
ELECTRONS
ENERGY-RANGE
MOLECULAR-DYNAMICS SIMULATION
TRACKS
DISPLACEMENT CASCADES
METALS
TEMPERATURE
ALLOYS
LATTICE
114 Physical sciences
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