Investigation of the NpZr and UZrNp systems

Abstract

Dilatometry, electron probe microanalysis and micrographic techniques were used to determine the melting points, the phase transformations and the phase relationships of the binary NpZr and of the U-rich ternary U-Zr-Np alloys. The high temperature allotropes γ-Np, γ-U and β-Zr are mutually miscible. The mutual solubility of the allotropic forms α-Zr with α- and β-U is, on the contrary, relatively poor both in the binary and in the ternary alloys. No ternary compounds were detected. The addition of Zr leads to an increase in the melting points of the U-Np alloys. A tentative NpZr phase diagram and three isothermal sections of the U-rich corner of the UZrNp phase diagram are presented.