Nucleation of α martensite crystals with (hhl) habits in elastic fields of dislocation loops

Abstract

An analysis was undertaken of the elastic field of dislocation loops in the form of parallelograms (or rectangles) in which the basic element is a pair of [110] line segments in the original fee phase. It was found that in this field wider possibilities exist for invariant-plane deformations to take place than in the elastic field of an individual dislocation, since the latter varies significantly with changes not only in the polar angle θ but also in the spatial coordinates. The likely causes of the change in the habits of a martensite from (557) to (225) are discussed within the concept of the heterogeneous nucleation and wave growth of martensite (near a dislocation loop). The nucleation of crystals with (225) habits is associated with an elastic field region having a local maximum in the relative change of volume.