Microstructural changes and their effect on hardening in neutron irradiated Fe-Cr alloys

JOURNAL OF NUCLEAR MATERIALS

卷:519

Article

Bhattacharyya, Dhriti^1,4  Yamamoto, Takuya²  Wells, Peter²  Marquis, Emmanuelle³  Bachhav, Mukesh³  Wu, Yuan²  Davis, Joel¹  Xu, Alan¹  Odette, G. Robert² 

[1] Australian Nucl Sci & Technol Org, Nucl Fuel Cycle Res, New Illawarra Rd, Lucas Heights, NSW 2234, Australia

[2] Univ Calif Santa Barbara, Dept Mat, Santa Barbara, CA 93106 USA

[3] Univ Michigan, Dept Mat Sci & Engn, Ann Arbor, MI 48109 USA

[4] Univ New South Wales, Sch Mat Sci & Engn, Sydney, NSW 2052, Australia

关键词: Fe-Cr steels;    Neutron irradiation;    Irradiation hardening;    Dislocation loops;    alpha ' precipitates;    TEM;   

DOI  :  10.1016/j.jnucmat.2019.03.022

来源: Elsevier

【 摘 要 】

A series of Fe-3 to 18 at.% Cr binary ferritic alloys were neutron irradiated side by side, in the Advanced Test Reactor (ATR) at a temperature of similar to 320 degrees C to a dose of similar to 1.8 dpa. Three types of features that form under irradiation are relevant: (i) solute clusters; (ii) alpha' precipitates; and, (iii) dislocation loops. The size and number density of the precipitates and loops were measured by transmission electron microscopy (TEM) and compared to previous atom probe tomography (APT) observations. The loop density systematically decreases with increasing Cr, while the number of alpha' precipitates increase at 9Cr and above. A major objective of this work is to estimate the dispersed barrier obstacle strength factors (a(j)) for loops, clusters and alpha' precipitates, based on the combined microstructural observations and corresponding irradiation hardening measurements. Standard dispersed barrier-hardening models and computationally derived superposition rules were least square fit to determine the a(j). The optimized hardening predictions are in very good agreement with experiment if mixed linear sum and root square sum superposition rules are used. Five increments of 168 h isochronal anneals of the 6Cr alloy between 300 and 400 degrees C coarsened the loops, while 300 h anneals of the 18Cr at 500 and 600 degrees C coarsened and dissolved the alpha' precipitates, respectively, consistent with the Fe-Cr phase diagram. (c) 2019 Elsevier B.V. All rights reserved.

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