ALLOYING BEHAVIOR IN SELECTED NEPTUNIUM BINARY-SYSTEMS - THE ROLE OF 5F BONDING

We have undertaken to establish the phase relations for selected binar y alloy systems of Np with another actinide or with a d-block transiti on metal. Empirical data obtained by differential thermal analysis and powder X-ray diffraction have been supplemented by elementary modelin g procedures and correlations with similar alloy systems to propose th e primary features of selected phase diagrams. The initial focus of th ese investigations has been on the Np-Am, Np-Zr and, most recently, th e Np-Fe systems. The findings for the former two systems are summarize d, and preliminary results for the Np-Fe system are reported. The pote ntial role of 5f bonding in determining alloying behavior is discussed in conjunction with regular-solution model predictions to address uni que features evident in certain Np ahoy systems.