Simulation of UAl 4 growth in an UAl 3/Al diffusion couple

Abstract

In this work the growth of the UAl 4 phase in an UAl 3/Al diffusion couple is treated as a planar moving boundary problem due to diffusion of Al and U atoms in the direction perpendicular to the interface surface. The diffusion problem was carried out by the DICTRA simulation package which combines data evaluated by Thermo-Calc with a mobility database. A thermodynamic database of the U–Al system, suitable for the Thermo-Calc code, was composed using data from literature. The mobility database was assessed from reported experimental growth of the UAl 4 phase at different temperatures. The Al tracer diffusion coefficient in the UAl 4 phase, D Al ∗ ( UAl 4 ) ( m 2 / s ) = 2.7 × 10 - 1 exp ( - 209500 ( J / mol ) / RT ) , is obtained under the assumption that uranium mobility is negligible.