Thermal diffusivity degradation and point defect density in self-ion implanted tungsten

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http://hdl.handle.net/10138/343367

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Reza , A , Yu , H , Mizohata , K & Hofmann , F 2020 , ' Thermal diffusivity degradation and point defect density in self-ion implanted tungsten ' , Acta Materialia , vol. 193 , pp. 270-279 . https://doi.org/10.1016/j.actamat.2020.03.034

Title: Thermal diffusivity degradation and point defect density in self-ion implanted tungsten
Author: Reza, Abdallah; Yu, Hongbing; Mizohata, Kenichiro; Hofmann, Felix
Contributor organization: Materials Physics
Department of Physics
Date: 2020-07
Language: eng
Number of pages: 10
Belongs to series: Acta Materialia
ISSN: 1359-6454
DOI: https://doi.org/10.1016/j.actamat.2020.03.034
URI: http://hdl.handle.net/10138/343367
Abstract: Using transient grating spectroscopy (TGS) we measure the thermal diffusivity of tungsten exposed to different levels of 20 MeV self-ion irradiation. Damage as low as 3.2 × 10−4 displacements per atom (dpa) causes a measurable reduction in thermal diffusivity. Doses of 0.1 dpa and above, up to 10 dpa, give a degradation of ̴55% from the pristine value at room temperature. Using a kinetic theory model, the density of irradiation-induced point defects is estimated based on the measured changes in thermal diffusivity as a function of dose. These predictions are compared with point defect and dislocation loop densities observed in transmission electron microscopy (TEM). Molecular dynamics (MD) predictions are combined with the TEM observations to estimate the density of point defects associated with defect clusters too small to be probed by TEM. When these “invisible” defects are accounted for, the total point defect density agrees well with that estimated from TGS for a range of doses spanning 3 orders of magnitude. Kinetic theory modelling is also used to estimate the thermal diffusivity degradation expected due to TEM-visible and invisible defects. Finely distributed invisible defects appear to play a much more important role in the thermal diffusivity reduction than larger TEM-visible dislocation loops. This work demonstrates the capability of TGS, in conjunction with kinetic theory models, to provide rapid, quantitative insight into defect densities and property evolution in irradiated materials.
Subject: ALLOYS
CONDUCTIVITY
DAMAGE PRODUCTION
ELASTIC PROPERTIES
ELECTRICAL-RESISTIVITY
EVOLUTION
Fusion materials
IRRADIATION
MATERIALS CHALLENGES
Point defects
TEMPERATURE
TRANSIENT GRATING SPECTROSCOPY
Thermal conductivity
Transient grating spectroscopy
114 Physical sciences
Peer reviewed: Yes
Rights: cc_by_nc_nd
Usage restriction: openAccess
Self-archived version: acceptedVersion


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