Deformation induced transformation in as-quenched uraniums at. % titanium alloy

The effect of plastic deformation on the structure of as-quenched U-4 at. % Ti alloy was studied by X-ray diffraction and transmission electron microscopy. The plastic deformation of waterquenched U-Ti martensite causes the diffusionless formation of the delta phase (U₂Ti) identified in the electron diffraction patterns. An atomistic model of the diffusionless α′ → δ transition is proposed. The model is based on the observation that during quenching a decomposition reaction occurs and the final martensite consists of alternating Ti-poor and Ti-rich regions with a modulation wavelength of about 15 nm. It is suggested that the Ti-rich regions are ordered with a U/Ti ratio of 2:1. When the alloy is subjected to plastic deformation these Ti-rich regions transform diffusionlessly into the delta phase.