Enhancing high-temperature strength of B4C-6061Al neutron absorber material by in-situ Mg(Al)B2

The industrial development of dry storage method of spent nuclear fuels strongly requires the low-cost B4C-Al neutron absorber materials (NAMs) with high strength and high stability at elevated temperatures. In the present work, the B4C-6061Al composites were fabricated by powder metallurgy method with different hot-pressing temperatures. Microscopic analysis showed that as hot-pressing temperatures increased from 560 degrees C to 630 degrees C, the interfacial reactions became severe, resulting in the formation of Al3BC and Mg(Al)B-2 compounds. The mechanical properties of the composites were enhanced by the interfacial reactions, specifically, the tensile strength of the sample hot-pressed at 630 degrees C was 40-59% higher than that at 560 degrees C at testing temperatures from room temperature up to 350 degrees C. Moreover, the high-temperature-pressed sample maintained the invariant strength level after suffering annealing at 400 degrees C for 8000 h. Characterization of the fractured composite indicated that the Mg(Al)B2 nanorods which effectively impeded the dislocation movement and grain boundary sliding provided a significant contribution to the composite strength. (C) 2019 Elsevier B.V. All rights reserved.