α-Phase transformation kinetics of U-8 wt% Mo established by in situ neutron diffraction

JOURNAL OF NUCLEAR MATERIALS

卷:477

Article

Steiner, M. A.¹  Calhoun, C. A.¹  Klein, R. W.¹  An, K.²  Garlea, E.³  Agnew, S. R.¹ 

[1] Univ Virginia, Mat Sci & Engn, 395 McCormick Rd, Charlottesville, VA 22904 USA

[2] Oak Ridge Natl Lab, Chem & Engn Mat Div, Spallat Neutron Source, Oak Ridge, TN 37831 USA

[3] Y-12 Natl Secur Complex, Oak Ridge, TN 37831 USA

关键词: U-Mo alloys;    Neutron diffraction;    Time-temperature-transformation diagram;    Transformation kinetics;    Eutectoid decomposition;   

DOI  :  10.1016/j.jnucmat.2016.05.016

来源: Elsevier

【 摘 要 】

The a-phase transformation kinetics of as-cast U - 8 wt% Mo below the eutectoid temperature have been established by in situ neutron diffraction. alpha-phase weight fraction data acquired through Rietveld refinement at five different isothermal hold temperatures can be modeled accurately utilizing a simple Johnson-Mehl-Avrami-Kolmogorov impingement-based theory, and the results are validated by a corresponding evolution in the g-phase lattice parameter during transformation that follows Vegard's law. Neutron diffraction data is used to produce a detailed Time-Temperature-Transformation diagram that improves upon inconsistencies in the current literature, exhibiting a minimum transformation start time of 40 min at temperatures between 500 degrees C and 510 degrees C. The transformation kinetics of U - 8 wt% Mo can vary significantly from as-cast conditions after extensive heat treatments, due to homogenization of the typical dendritic microstructure which possesses non-negligible solute segregation. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

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