Production and examination of ternary Pu-Al-Ir intermetallic phases

Iridium is a container material for plutonia in radio-isotopic heat sources used for thermoelectric power generation in various US space missions. Aluminum flight hardware is present within the heat source service environment. This study was undertaken to evaluate possible reaction products that could result if the component metals interact at high temperatures such as in an explosion or fire. In this work, the reactivity of Pu with Al and Ir has been studied by examination of a reacted ternary specimen as quenched from the melt and then reexamined after annealing. Two ternary intermetallic phases were identified by electron microprobe examination: The major phase was found to have a stoichiometry corresponding to the previously unreported compound PuAlIr. The minor phase was also found to be of ternary composition but more Al-rich, X-ray diffraction analysis of the major ternary phase is described. No structural determination has been made, but the X-ray data are included. Differential thermal analysis has shown both phases to be stable to at least 14500C. (orig.)