Metallurgy of PuGa alloys: the latest insights into d-phase stability and oxidation

摘要

Plutonium, which was discovered in 1942, displayshighly unusual behaviour that makes it the most complexelement in the periodic table. Indeed, plutonium metal hassix allotropic phases between room temperature and itsmelting point at ambient pressure. The δ-phase of plutoniumis the most ductile and oxidizes at a lower rate incomparison with the other phases, especially the α-phase;therefore it is the most interesting phase for metallurgicalapplications.For Pu alloys, the existence domains of these phasesare particularly sensitive to temperature, time, stress andalloy chemical composition. At room temperature, the stablephase is the brittle (simple monoclinic) α-phase. The hightemperature(face-centred cubic) δ-phase, which is stablefrom 315 to 457℃, can also be held at room temperatureand pressure by alloying plutonium with “δ-phasestabilizing” elements such as Al, Am, Ce and Ga.