Ion beam induced spinodal decomposition and amorphization in the immiscible bilayer system UMo/Mg

High density fuel uranium-molybdenum (UMo) alloy embedded in an Mg matrix has been investigated as a candidate material for high density fuel of research reactors. UMo/Mg bilayers were prepared and irradiated with swift heavy ions to simulate damages created by fission fragments during in-pile irradiation. Scanning transmission electron microscopy and X-ray microdiffraction reveal the micro-structural evolution during irradiation including amorphization and spinodal decomposition. Spinodal decomposition during irradiation results in a chessboard-like pattern with a U-rich and a U-poor phase. In addition, an irradiation-induced phase U0.9Mg0.1 has been found. In comparison to UMo embedded in an Al matrix, the diffusion reactions and the amorphous region are well detained.