High-heat flux Cu-0.8Y alloys investigated by positron annihilation spectroscopy

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Domínguez Reyes, R. and Monge, M. A. and Galiana, B. and Ortega Villafuerte, Yanicet and Muñoz, A. and Carro Sevillano, G. (2021) High-heat flux Cu-0.8Y alloys investigated by positron annihilation spectroscopy. Journal of alloys and compounds, 900 . ISSN 0925-8388

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Official URL: http://dx.doi.org/10.1016/j.jallcom.2021.163430




Abstract

This work studies the thermal stability of the microstructure and the evolution of the defects of two high-heat flux Cu-0.8 wt%Y alloys fabricated following two alternative powder metallurgy routes. One batch was produced by direct hot isostatic pressing (HIP) consolidation of Cu-0.8 wt%Y pre-alloyed atomized powders while an additional ball milling processing step was introduced before HIP sintering for the second alloy. The stability and recovery characteristics of the vacancy type defects in these alloys in the as-produced state and after processing by severe equal channel angular pressing to achieve a refine microstructure have been investigated by positron lifetime and coincidence Doppler broadening measurements in samples subjected to isochronal annealing from room temperature to 900 degrees C. Microhardness measurements and electron transmission microscopy analysis have also been performed to support the results obtained from the positron annihilation spectroscopy analysis techniques. The recovery curves of the positron lifetime and S-W plots show a recovery stage in agreement with the recovery stage V for Cu. However, a full recovery is not accomplished, and a stage that reverts the previous recovery takes place after annealing above similar to 600 degrees C, that leads to the formation of very stable defects at temperatures up to 900 degrees C, identified as vacancy aggregates and nanocavities. The characteristic shape of the coincidence Doppler broadening indicates that the dispersed Y-O particles in the Cu matrix appear to be responsible for stabilizing the vacancy aggregates and nanocavities for temperatures above 600-700 degrees C.


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© 2022 The Author(s). Published by Elsevier B.V. CC_BY_NC_ND_4.0
This research was supported by the Spanish Ministerio de Economia y Competitividad (MINECO) in the form of Project ENE2015-70300-C3-2-R and by the Regional Government of Madrid (Spain) through TECHNOFUSIÓN(III)CM (S2018/EMT-4437), and Comunidad de Madrid (Spain) - multiannual agreement with UC3M (“Excelencia para el Profesorado Universitario” - EPUC3M14) - Fifth regional research plan 2016–2020; and also Spanish Ministerio de Ciencia e Innovación through project DAMAINSOL [grant number RTI2018-101020-B-I00].

Uncontrolled Keywords:Fine-grained materials; Mechanical-properties; Defect structure; Lifetime spectroscopy; Neutron-irradiation; Cu; Microstructure; Vacancies; Metals; Copper alloys; Oxide dispersion strengthened; Positron annihilation; High-heat flux materials; Equal channel angular pressing; Reinforced materials
Subjects:Sciences > Physics > Materials
Sciences > Physics > Solid state physics
ID Code:70485
Deposited On:21 Feb 2022 15:29
Last Modified:22 Feb 2022 08:39

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