The crystallography of the δ to α martensitic transformation in plutonium alloys

Abstract

The CRAB formulation of the theory of martensite crystallography has been applied to the δ to α phase transformation in plutonium alloys. The low symmetry of the monoclinic α-phase results in 41 lattice invariant transformation shear modes being considered possible. The predictions, when these shears are used with the three available correspondences have been analysed and the 20 most likely mechanisms selected for presentation. Because of the lack of experimental information with which to compare the results it is difficult to select the best mechanism. However twinning of the product phase on (001) using the third correspondence is suggested. This has a habit plane near {258} δ which is the crucial piece of information which needs to be checked experimentally. Further theoretical work on the atomic shuffles associated with the correspondence also needs to be carried out.