Intermetallic formation and interdiffusion in diffusion couples made of uranium and single crystal iron

摘要

We studied the interfacial phase formation and diffusion kinetics in uraniumeiron diffusion couples. A comparison was made between polycrystalline uranium (U) bonded with polycrystalline iron (Fe-P) and polycrystalline uranium bonded with single crystalline Fe (Fe-SC). After thermal annealing at 575 degrees C, 600 degrees C, 625 degrees C and 650 degrees C, respectively, diffusion and microstructures at the interface were characterized by scanning electron microscopy and transmission electron miscopy. The presence of grain boundaries in iron has a significant influence on interface reactions. In comparison with U-Fe-P system, interdiffusion coefficients of the U-Fe-SC system are significantly lower and were governed by much higher activation energies. Integrated interdiffusion coefficients and intrinsic diffusion coefficients were obtained. The intrinsic diffusion coefficients show faster diffusion of iron atoms in both U6Fe and UFe2 intermetallic phases than uranium. (C) 2015 Published by Elsevier B.V.