Methodology for describing the α → β phase transformation in plutonium

The reaction mechanism of the α → β phase transformation in plutonium has been revisited using non-isothermal methods. The conditions for obtaining reproducible reaction parameters which take into account sample recovery from the effects of a previous phase transformation have been examined. The reaction mechanism for the α → β phase transformation performed on the material and under the conditions explained in this work can be described in considerably more detail than has previously been reported by following the change in activation energy as a function of the degree of transformation. This approach allows for a meaningful representation of the multi process reaction mechanism of the α → β phase transformation which reflects the change in influence of the governing mechanisms of nucleation, growth and impingement at different stages of the reaction.

► Impact of thermal conditioning on plutonium α → β phase transformation parameters. ► Conditions for sample recovery from a previous phase transformation in plutonium. ► Non-isothermal treatment of the plutonium α → β phase transformation mechanism. ► Activation energy shown as a function of transformation reveals complex mechanism. ► Proposed framework for comparing phase transformations in other plutonium systems.