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Microstructure characterization and phase field analysis of dendritic crystal growth of γ-U and BCC-Mo dendrite in U–33 at.% Mo fast reactor fuel

  • Sibasis Chakraborty (a1), Gargi Choudhuri (a2), Perepa Subramanya Somayajulu (a3), Renu Agarwal (a4) and Kirity Bhusan Khan (a3)...

U–Mo metallic alloy is considered as an advanced fast reactor and research reactor fuel material. U–33 at.% Mo has a higher melting point than that of pure uranium metal. This provides a higher safety margin against fuel melting and diminishes fuel and clad interaction. The metallic fuels are fabricated through a melting-casting route, and the cast microstructure of U–33 at.% Mo has been characterized using optical microscope, scanning electron microscopy—energy dispersive spectroscopy, and Electron back scattered diffraction. These microstructures show dendrites of two different morphologies: (i) the γ-(U) dendrite with secondary branches and (ii) the equiaxed (Mo) dendrite without secondary branches and surrounded by a peritectic reaction product. In this article, for the first time, a phase field model has been developed for U–Mo alloys to understand the morphological evolution and the associated microsegregation of γ-(U) dendrites in the U–33 at.% Mo alloy. The evolution of the concentration and temperature field with the time and the effect of undercooling on the growth velocity of γ-(U) and (Mo) dendrites has been studied.

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Journal of Materials Research
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