Analysis of Crystallography Structure on U–6zr–Xnb Alloys as Reactor Fuel Material and its Correlation with Phase Transformation and Microstructure

Abstract

In this study, solid solution U – 6Zr –xNb alloys (x = 0, 1, 4, and 7 wt%) have been successfully prepared using the conventional arc melting method with raw materials of U, Zr, and Nb metals according to stoichiometric composition. According to the results of elementary analysis using EDS, the Nb content was obtained as much as 0.65, 4.45, and 8.00 wt.%, respectively, for alloy compositions x = 1, 4, and 7 wt.%. The results of XRD pattern refinement showed that at alloy compositions x = 0 and x = 1 wt.%, a single phase α-U with orthorhombic structure, space group C m c m (63) and atomic density of 18.878 g/cm-3 and 18.631 g/cm-3 respectively. At the alloy composition, x = 4 wt.% is the transition point of phase change between the α-U and γ-U phases with mass fractions of 11.19% and 88.81%, respectively. While at the alloy composition, x = 7, wt.% has formed a single phase γ-U with a cubic structure (bcc), space group of I m [[EQUATION]] m (229) and atomic densities of 17.752 g/cm-3 and 17.751g/cm-3 , respectively. The increasing content of Nb atoms in the structure causes all structural parameters to change, leading to the γ-U structure. The results of microstructural analysis using SEM and optical microscope also show the same phenomenon, namely, the change in morphology leads to the γ-U morphology. Considering that U – 6Zr –7Nb alloy has a high density of 15.3709 g/cc, this alloy can be applied as a candidate for nuclear reactor fuel. The correlation between changes in these structural parameters and the presence of phase transformation and microstructure has been discussed in this paper.

Keywords: nuclear fuel, U -6Zr -xNb alloy, crystal structure, transformation, microstructure, high density