Layer growth during interdiffusion in the aluminum uranium alloy system

Abstract

Interdiffusion in the aluminum-uranium system has been investigated over the temperature range 400°–600° C, and over the pressure range 1 1 4 −10 tsi for diffusion times of 24 hours and less. The pressureinduced increase in UAl 3 layer thickness has been confirmed. Interesting correlations have been shown to exist between annealing time, annealing temperature, and applied pressure on the one hand, and the nature and distribution of structural defects in the UAl 3 diffusion zone on the other. It has been demonstrated that the solubility range within the UAl 3 phase must be at least 2.6 at % uranium. It has been shown that the growth of the UAl 4 and UAl 2 phases in incremental couples is much slower than the growth of UAl 3 in aluminum-uranium couples. Finally, it is proposed that the effect of pressure on UAl 3 layer growth is primarily mechanical in that higher pressures repress the tendency for the formation of macroscopic voids and thus effectively increase the cross-sectional area available for interdiffusion.