Conservation de germes de phase α en phase β dans l'uranium faiblement allie

Phase Transformations in the Actinides.

“…Using a cooling rate of t°C/hr, they also noted that the j3 -» a transition temperature decreased with an in crease in the prior temperature within the j3 phase. In agreement with these results fieaudier et al (125) noted that an increase in the P temperature or in the time at this temperature caused an in crease in the incubation period of the following /5 -* a reaction and a decrease in the transformation rate. A cooling rate of b°C/hr was used for U and U alloyed with small additions of Cr, Mn, and Ho.…”

“…-39-Beaudier ttal.,' 101 ) on studying the influence of j8 tempera ture over a 100°C range within the 0 phase, also noted the effect of the /3 temperature on the subsequent temperature at which the P -a transition is initiated. Using dilatometry as a criterion for anisotrcpy, tha authors concluded that as the prior 0 tempera ture is increased the original orientation in the subsequent a phase was progressively eliminated.…”

Precipitates Morphology in Iron-Diluted U–Fe Alloys

“…a transformation mechanism, as was reported by Mott and Haines [17]. The irregular shape of the a-U grains could also be correlated to shear mechanism transformation, as was done by Beaudier et al [8]. Figure 5 shows ''needle-like'' precipitates of U 6 Fe, which were seen in some U-0.2 wt% Fe samples.…”

“…Thus, control of the microstructures by different heat treatment processes allows determining the mechanical properties. Various investigators [3][4][5][6][7][8] showed that addition of small amounts of certain solutes (less than 1-2 at.%), of which Cr was mostly studied, retains the b ? a phase transformation at lower temperature followed by an isothermal transformation.…”