The magnetic origin of anomalous high-temperature stability of dislocation loops in iron and iron-based alloys

The dominant occurrence of the b = a(001) prismatic edge dislocation loops in iron and iron-based alloys irradiated at temperatures approaching 500 degrees C is a striking anomaly distinguishing iron and its alloys from other bcc metals. It is surprising that the a(00 I) dislocation loops form at all, since there is an alternative b = a/2(111) dislocation loop configuration that, according to the conventional isotropic treatment of elasticity, has a lower self-energy. In this paper we highlight the magnetic aspect of the problem and note the fundamental link between the alpha-gamma phase transition, the elastic anisotropy of iron, which is particularly significant at elevated temperatures, and thermal magnetic fluctuations. Crown Copyright (c) 2009 Published by Elsevier B.V. All rights reserved.