PNNL

Abstract

Low-enriched uranium alloyed with 10 wt% molybdenum (U-10Mo) is currently being investigated as an alternative fuel for the highly enriched uranium used in several of the United States’ high performance research reactors. Development of the methods to fabricate the U-10Mo fuel plates is currently underway and requires fundamental understanding of the mechanical properties at the expected processing temperatures. In the first part of this series, it was determined that the as-cast U-10Mo had a dendritic microstructure with chemical inhomogeneity and underwent eutectoid transformation during hot compression testing. In the present (second) part of the work, the as-cast samples were heat treated at several temperatures and times to homogenize the Mo content. Like the previous as-cast material, the “homogenized” materials were then tested under compression between 500 and 800°C. The as-cast samples and those treated at 800°C for 24 hours had grain sizes of 25-30 ?m, whereas those treated at 1000°C for 16 hours had grain sizes around 250 ?m before testing. Upon compression testing, it was determined that the heat treatment had effects on the mechanical properties and the precipitation of the lamellar phase at sub-eutectoid temperatures.