X-Ray Diffraction Study of the Stress-Induced Martensitic Phase Transformation in the Uranium-6.9 to 7.7 Wt % Niobium Alloys.

摘要

X-ray diffraction data from polycrystalline uranium-niobium (U-Nb) alloys with compositions of 6.9 to 7.7 wt % niobium showed evidence of stress-induced gamma sup 0 implies alpha '' (tetragonal implies monoclinic) phase transformations when specimens were deformed in tension. These transformations appeared almost continuously with respect to strain because lines from the gamma sup 0 phase appeared to shift with increasing strain to positions near those expected for lines from the corresponding alpha '' phase. An analysis of these data and observations in previous studies indicate that the gamma sup 0 implies alpha '' stress-induced martensitic transformation was thermoelastic, and the data could best be explained by elastic accommodation coupled with a small, first-order, discontinuous change. 23 refs., 14 figs., 1 tab. (ERA citation 14:004713)