Masters Theses

Date of Award

3-1987

Degree Type

Thesis

Degree Name

Master of Science

Major

Metallurgical Engineering

Major Professor

C. R. Brooks

Committee Members

J. E. Spruiell, A. J. Pedraza

Abstract

The martensitic reaction in five Uranium-Nb alloys (14.5,15.0, 15.5, 15.5, and 16.0 at% Nb) was studied by means of x-ray diffraction experiments in order to establish the temperature range of this reaction. The experiments were carried out in a cryostat on a diffractometer in which minimum temperatures close to liquid N2 temperature were obtained. All the samples were solution heat treated at 800°C and water quenched. They were then electropolished prior to diffraction experiments. The diffraction patterns were taken from about 25°C down to about -190°C. The intensity-Bragg angle data were digitized and the relative amounts of the parent phase γ° and the martensite phase α" were determined by means of a peak separation and analysis program.

The 14.5 at% Nb alloy was completely martensitic at 25°C, and the 16.0 at% Nb alloy remained completely γ° phase down to -192°C. For the other alloys, as the temperature decreased, the amount of the martensitic α" phase increased, and that of γ° decreased. For all three alloys, the temperature was below the lowest temperature of measurement (-192°C), and the Ms was above 25°C. At a given temperature, the amount of α" decreased with increasing Nb content.

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