Laves phases in the U – Mo – Zr system

• Published in: Journal of alloys and compounds 2021-05, Vol.863, p.158070, Article 158070
• Main Authors: Sales Morais, Nathanael Wagner, Schön, Cláudio Geraldo
• Format: Article
• Language: English
• Subjects: A: Nuclear reactor Materials; B: Forming processes; B: Precipitation; C: Crystal structure; C: Microstructure; D: X-ray diffraction (XRD)
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.158070

Molybdenum and zirconium are known as alloying elements for uranium, used in the production of metallic nuclear fuels. Based on the binary systems it is expected that compound Mo2Zr, a Laves phase with the C15 structure, should be present in ternary alloys. We report here the existence of a C14 variant, in parallel to the C15 phase, both dissolving uranium. This confirms the heuristic hypothesis of Stein (2011) [24] about the stabilization of Laves variants depending on the crystallographic arguments. The relation of the presence (attested by X-ray diffraction) of both variants with the composition and with processing is discussed with regard of the microstructure developments in mechanical processing and heat treatments of two alloys with compositions U – 3 Mo – 9 Zr and U – 9Mo – 3 Zr (in wt%). [Display omitted] •Microstructure evolution with processing was investigated in U - Zr - Mo alloys.•“As cast” microstructures present Zr-rich dendrites which dissolve with processing.•Uranium content in matrix and precipitation are controlled by the Zr-rich particles.•C15 Laves Mo2(Zr,U) phase exist in both alloys dissolving up to 20 at% U.•In alloys U - 9 Zr - 3 Mo the C14 Laves phase is found, dissolving more Zr and U.