Interdiffusion studies on hot rolled U-10Mo/AA1050

Abstract

The U-Mo alloys are investigated with the goal to become nuclear material to fabricate high-density fuel elements for high performance research reactors. The enrichment level (20% 235U) suggests that the U-Mo alloys should be between 6 to 10 wt. (%), which can reach up to 9 gU.cm-3 in fuel density. Nevertheless, the U-Mo alloys are very reactive with Al. Interdiffusion reaction products are formed since nuclear fission promotes chemical interaction layer during operation, leading to potential structural failure. Present studies were made with treated hot rolled diffusion couples of U-10Mo inserted in Al (AA1050). The U-10Mo/AA1050 pairs were treated in two temperatures (150 °C and 550 °C) with three soaking times (5, 40 and 80 hours). From microstructure analyses, rapid diffusion of Al happened inside U-10Mo in the first heating at 540 °C during 15 minutes, reaching 8 at% Al in a range of 170 μm towards U-10Mo. Longer time at 550 °C treatment maintain this level of Al-content up to 1000 μm inside U-10Mo. In this study, the results suggested the formation of a barrier made by residual elements, which promoted little interdiffusion phenomena between U-10Mo and alloy AA1050. Silicon co-diffusion with Al, along the interdiffusion line, is thought to be an important indication for this interdiffusion blockage. © 2012.