Abstract: "The niobium-carbon system has been determined by X-ray and metallographic examination of sintered and arc-cast alloys. Two carbides exist: hexagonal Nb2C with a limited range of homogeneity, and cubic NbC with a solubility range from 8.25 to 10.25 weight per cent carbon. Dilute alloys freeze by eutectic reaction at 2230 C. The solubility of carbon in niobium is 0.80 at the eutectic temperature, but this decreases rapidly with temperature. Metallographic evidence indicates a peritectic reaction between melt, Nb2C, and NbC; alloys richer in carbon than NbC freeze by eutectic reaction."

The following report is the final technical report on a series of reports under contract AT(11-1)-515, titled "Niobium Phase Diagrams", covering the period from April 15, 1957 to April 16, 1960.

Monthly report the progress and development of improved zirconium alloys for service in superheated water and steam. This report covers the period between April 1 to April 31, 1961 and was conducted by the United States and the European Atomic Energy Community (EURATOM).

"The magnetic properties of color centers were studied to obtain information regarding electron traps in insulators. Experiments designed to determine the equation governing the recovery of resonance after saturation were carried out. Relatively large samples were prepared by the method of additive coloration. KCl and RbCl crystals were used. Resonance saturation as a function of concentration was investigated and no significant dependence found. Measurements of the unsaturated susceptibility were made at liquid nitrogen and liquid helium temperatures. The bleaching of the F-center to form the B-band produced a different resonance. The equipment for observing the saturation and recovery of a portion of the resonance at 4 deg K is described. A theoretical examination was made of the interaction between the vibration of the ions around a negative-ion vacancy in an alkali halide and an electron trapped at that site. (M.C.G.)."