Reproducible phase transformation in a single Pu–1.9 at.% Ga specimen

In situ X-ray diffraction study of the δ to α′ isothermal martensitic transformation kinetics in a Pu–Ga alloy

“…A non-homogenized Pu-Ga alloy would complicate the study of the transformation kinetics. Because the samples used in the experiments described here were thermally cycled between 375°C and À160°C after the homogenization treatment, they were annealed again at 375°C for 8 h to remove strains from previous phase transformations; previous work shows that this treatment is sufficient to effectively return the material to its initial homogenized condition [13]. The samples were then conditioned longer than 8 h to maximize the d ?…”

Impact of compressive pressure on the phase stability and transformation behaviour of δ-phase stabilised plutonium alloys

“…This transformation is reported as a series of endothermic peaks at temperatures around 80 C [10][11][12]14].…”

“…This is especially the case with regards to the impact of experimental conditions and the limits and strengths of the different analytical techniques used. The stability of the a 0 -phase for a particular alloy composition, appears to be governed by the methods that are used to induce it [1][2][3][4][5][9][10][11][12][13][14]. The a 0 -phase may revert on heating, directly to the d-phase or by following an indirect path via the b-phase and g-phase (of pure plutonium).…”

“…The a 0 -phase may revert on heating, directly to the d-phase or by following an indirect path via the b-phase and g-phase (of pure plutonium). The direct a 0 -d phase transformation follows a martensitic mechanism, typically referred to as the burst transformation, comprising a number of low intensity peaks occurring over a wide temperature range [10]. Any a 0 -phase transforming via the direct path is reported to revert back to the d-phase at temperatures within the a 0 -phase stability temperature range (Table 1), leaving a single phase fully d-phase stabilised alloy.…”

“…[10][11][12]31,32]. The sum enthalpy value of the peaks was 0.4 AE 0.1 J g À1 .In order to provide an understanding of the extent of direct transformation, as a reference enthalpy for the complete a 0 -d phase transformation has not been determined unambiguously, an evaluation was made based on the estimated value of 17 J g À1[2,25].…”