A differential scanning calorimetry study of the kinetics of the β → γ phase transformation in plutonium

A number of DSC studies have determined the onset temperature and the enthalpy change for the β → γ phase transformation in plutonium but these have all been conducted by measuring the phase transformation parameters immediately following the α → β phase transformation which will have a considerable impact on the reaction kinetics.The thermal history and condition of a specimen will have a significant effect on the reaction parameters of a solid phase transformation. The current study examines the influence of the specimen condition and more specifically the impact of a previous phase transformation and the mode of formation of the β-phase from both the α-phase and from the γ-phase on the β → γ phase transformation parameters and reaction kinetics.The impact of the β-phase condition on the transformation parameters of the β → α phase transformation is also examined.

► Significant impact of thermal history on β → γ phase transformation parameters. ► Stability of the parent β-phase on the kinetics of the β → γ phase transformation. ► Comparison of β → γ transformation parameters for β-phase formed from α-phase and from γ-phase. ► Comparison of β → γ reaction kinetics for β-phase formed from α-phase and from γ-phase. ► Impact of β-phase condition on the reaction parameters for the β → α phase transformation.