The Uranium-Carbon System

Abstract

An investigation of the uranium‐carbon system has been made and a constitutional diagram drawn on the basis of melting point, x‐ray, and metallographic data. Three carbides of uranium have been detected and identified: UC , U2C3 , and UC2 . No compounds have been found containing a carbon content higher than that of UC2 . UC and UC2 are completely soluble in each other at elevated temperatures, forming a solid solution. The solid solution phase cannot be retained on cooling to room temperature in alloys containing between about 5.0 to 9.0 weight per cent carbon. A Widmanstätten type of precipitation takes place on cooling, leaving either UC precipitated in a UC2 matrix or vice versa, depending on the carbon content of the alloy. In alloys containing above about 9.0 weight per cent total carbon, UC can quite effectively be retained in solid solution by quenching from temperatures above about 1800°C.

Mechanism of Direct Electrochemical Reduction of Solid UO2to Uranium Metal in CaCl2-48mol% NaCl Melt

“…The layer may also be removed during washing of the pellet. The U-C phase diagram 44 shows the existence alpha-uranium + UC phase at temperatures below 923 K, but XRD analysis of the polished surface of the pellets in the present study didn't reveal the existence of any carbide phase in the sample. Probably, the uranium carbides were not formed under the present set of experimental conditions and/or the polishing might have removed negligible quantities carbides present at the surface, if formed.…”