Grain boundary engineering to control the discontinuous precipitation in multicomponent U10Mo alloy. (1st June 2018)

• Record Type: Journal Article
• Authors: Devaraj, Arun; Kovarik, Libor; Kautz, Elizabeth; Arey, Bruce; Jana, Saumyadeep; Lavender, Curt; Joshi, Vineet
• Is Part Of: Acta materialia. Volume 151(2018)
• Page Start: 181
• Page End: 190
• Publication Date: 2018-06-01
• Subjects: Grain boundaries -- Grain boundary segregation -- Microstructure -- Phase transformation -- Grain-boundary segregation-induced phase transformation; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.03.039
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: We demonstrate here that locally stabilized structure and compositional segregation at grain boundaries in a complex multicomponent alloy can be modified using high temperature homogenization treatment to influence the kinetics of phase transformations initiating from grain boundaries during subsequent low temperature annealing. Using aberration-corrected scanning transmission electron microscopy and atom probe tomography of a model multicomponent metallic alloy —uranium-10 wt% molybdenum (U-10Mo) a nuclear fuel, that is highly relevant to worldwide nuclear non-proliferation efforts, we demonstrate the ability to change the structure and compositional segregation at grain boundary, which then controls the subsequent discontinuous precipitation kinetics during sub-eutectoid annealing. A change in grain boundary from one characterized by segregation of Mo and impurities at grain boundary to a phase boundary with a distinct U2 MoSi2 C wetting phase precipitates introducing Ni and Al rich interphase complexions caused a pronounced reduction in area fraction of subsequent discontinuous precipitation. The broader implication of this work is in highlighting the role of grain boundary structure and composition in metallic alloys on dictating the fate of grain boundary initiated phase transformations like discontinuous precipitation or cellular transformation. This work highlights a new pathway to tune the grain boundary structure and composition to tailor the final microstructure of multicomponent metallic alloys. Graphical abstract: Image 1