PRE ALPHA-]BETA TRANSFORMATION IN HIGH PURITY PLUTONIUM

The small thermal effect which has been detected on heating just below the α-β equilibrium temperature of plutonium by differential thermal analysis has been interpreted previously as being caused by an endothermic reaction. Experiments involving the thermal, electrical and physical properties of high purity plutonium were conducted which show that the small thermal effect just prior to the α-β equilibrium transformation temperature is caused by the exothermic transformation of retained γ to α phase which becomes inoperative above the reported pre α→β temperatures. The pre α→β phenomenon in high purity plutonium can be increased with thermal histories that increase the retention of γ phase plutonium and conversely the effect can be eliminated by first transforming the metastable higher temperature phases to α phase plutonium. © 1969.