Metastable phases in Zr-Excel alloy and their stability under heavy ion (Kr2+) irradiation

JOURNAL OF NUCLEAR MATERIALS

卷:469

Article

Yu, Hongbing¹  Zhang, Ken¹  Yao, Zhongwen¹  Kirk, Mark A.²  Long, Fei¹  Daymond, Mark R.¹ 

[1] Queens Univ, Dept Mech & Mat Engn, Kingston, ON K7L 3N6, Canada

[2] Argonne Natl Lab, Div Mat Sci, 9700 S Cass Ave, Argonne, IL 60439 USA

关键词: Zr-Excel alloy;    Heavy ion irradiation;    Phase stability;    Chemi-STEM EDS;   

DOI  :  10.1016/j.jnucmat.2015.11.020

来源: Elsevier

【 摘 要 】

Zr-Excel alloy (Zr-3.5Sn-0.8Nb-0.8Mo, wt.%) has been proposed as a candidate material of pressure tubes in the CANDU-SCWR design. It is a dual-phase alloy containing primary hcp alpha-Zr and metastable bcc beta-Zr. Metastable hexagonal omega-Zr phase could form in beta-Zr as a result of aging during the processing of the tube. A synchrotron X-ray study was employed to study the lattice properties of the metastable phases in as-received Zr-Excel pressure tube material. In situ heavy ion (1 MeV Kr2+) irradiations were carried out at 200 degrees C and 450 degrees C to emulate the stability of the metastable phase under a reactor environment. Quantitative Chemi-STEM EDS analysis was conducted on both un-irradiated and irradiated samples to investigate alloying element redistribution induced by heavy ion irradiation. It was found that no decomposition of beta-Zr was observed under irradiation at both 200 degrees C and 450 degrees C. However, omega-Zr particles experienced shape changes and shrinkage associated with enrichment of Fe at the beta/omega interface during 200 degrees C irradiation but not at 450 degrees C. There is a noticeable increase in the level of Fe in the a matrix after irradiation at both 200 degrees C and 450 degrees C. The concentrations of Nb, Mo and Fe are increased in the omega phase but decreased in the beta phase at 200 degrees C. The stability of metastable phases under heavy ion irradiation associated with elemental redistribution is discussed. (C) 2015 Elsevier B.V. All rights reserved.

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