DOI: 10.1209/epl/i2002-00629-y


Europhys. Lett., 58 (2) , pp. 243-249 (2002)

Long-range atomic order in irradiated

L. D. Cussen^{1, 2, 3}, E. MacA. Gray⁴, A. P. Murani¹, S. J. Kennedy³ and B. A. Hunter<sup>3

1</sup>  Institut Laue-Langevin - 6 Rue Jules Horowitz, B.P. 156 X Grenoble Cedex 9, France
²  Victoria University of Technology - P.O. Box 14428, MCMC 8001, Australia
³  ANSTO - PMB 1, Menai NSW, 2234, Australia
⁴  School of Science, Griffith University - Brisbane 4111, Australia

(Received 12 July 2001; accepted in final form 25 January 2002)

Abstract
Atomic short-range order is commonly observed in alloys via a diffuse ( ) peak in neutron diffraction patterns. There has been speculation for many years on the existence and nature of any corresponding long-range order. A sample of has been irradiated in a high fast-neutron flux to produce a large number of crystal defects at around room temperature and thus facilitate the ordering process. Measurements of the diffuse neutron scattering from this sample demonstrate that long-range order has been induced in the sample, as evidenced by at least five Bragg peaks. This order is not seen in a reference sample prepared in identical fashion except for the irradiation. The Cowley short-range order parameters for both samples are calculated and a candidate structure for the long-range order is proposed.

PACS
61.50.Ks - Crystallographic aspects of phase transformations; pressure effects.
61.72.Ji - Point defects (vacancies, interstitials, color centers, etc.) and defect clusters.
61.80.Hg - Neutron radiation effects.


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