Mechanism for the {\alpha} -> {\epsilon} phase transition in iron

TL;DR

This paper proposes a new mechanism for the alpha-epsilon phase transition in iron, involving layer shuffles and a nucleation-propagation process, differing from previous models and requiring specific magnetic order.

Contribution

It introduces a novel transition pathway based on layer shuffles and a unique magnetic order, expanding understanding of iron's phase transformation.

Findings

Proposes a new transition path involving layer shuffles.

Suggests a different magnetic order is necessary for the transition.

Describes the process as akin to nucleation and propagation.

Abstract

The mechanism of the {\alpha}-{\epsilon} transition in iron is reconsidered. A path in the Burgers description of the bcc/hcp transition different from those previously considered is proposed. It relies on the assumption that shear and shuffle are decoupled and requires some peculiar magnetic order, different from that of {\alpha} and {\epsilon} phases as found in Density-Functional Theory. Finally, we put forward an original mechanism for this transition, based on successive shuffle motion of layers, which is akin to a nucleation-propagation process rather than to some uniform motion.