Gamma-phase homogenization and texture in U-7.5Nb-2.5Zr (Mulberry) alloy

This work investigates the phenomena of homogenization and texture of the γ phase in U-7.5Nb-2.5Zr (Mulberry) alloy prepared by induction melting and cold-rolling. The microstructural characterization of the as-cast and homogenized alloy (heat treated in γ phase region and then quenched in water), as well as the deformed state, was performed using optical and electron microscopy techniques, hardness testing and X-ray diffraction, employing the Rietveld method. The as-cast microsegregation was qualitatively observed by optical microscopy whereas the quantitative evaluation was obtained by electronprobe micro-analysis (EPMA). The homogenization state of the structure was evaluated after heat treatment at 1000 °C in a tube furnace for 5 h. It was found that this treatment is effective in eliminate dendritic segregation in this alloy.

The texture of the Mulberry alloy was studied by X-ray diffraction (XRD) in the γ-phase stabilized condition and deformed state (rolled at room temperature). The stabilized γ alloy showed moderate texture mainly on the components (0 2 3)<1 0 0> and (0 3 2)<1 0 0>. After 80% deformation, the sample showed a fiber texture (0 0 1)<u v w>, not commonly found in BCC metals, besides the γ fiber (1 1 1)<u v w> with intermediate intensity.