Crystallography of the δ→α phase transformation in a PuGa alloy

T. G. Zocco*, M. F. Stevens, P. H. Adler, R. I. Sheldon, Gregory B Olson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


The crystallography of the δ→α phase transformation in a Pu nominally 1.0 wt% Ga alloy has been examined through the application of Transmission Electron Microscopy (TEM), giving new insight into the martensitic nature of the transformation. This transformation is of particular interest because of its unusually large volume change of ∼20%. Direct examination by TEM has revealed (205)α twinning as a lattice invariant deformation mode, an orientation relationship giving near parallelism of the (111)δ and (020)α planes and the [110]δ and [100]α directions, and an α phase habit plane near (132)α. A survey of twinning in α-Pu has shown that the compound twinning system K1 = (205)α, K2 = (203)α, η1 = [502]α, η2 = [302]α requires the lowest shear and no lattice shuffling in a pseudo-structure closely related to α-Pu. Upon application of these experimentally determined parameters to established martensite crystallographic theory, it has been shown that a reasonable solution is obtained, giving a habit plane of (0.732, 0.535, 0.422)δ with a total transformation shape strain of m = 0.331, and a lattice invariant shear of m2 α = 0.014 corresponding to a twin fraction of 0.194. The results strongly suggest this transformation occurs via a martensitic mechanism despite the large volume change.

Original languageEnglish (US)
Pages (from-to)2275-2282
Number of pages8
JournalActa Metallurgica Et Materialia
Issue number11
StatePublished - Jan 1 1990

ASJC Scopus subject areas

  • Engineering(all)


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