Phase transformation of metastable discontinuous precipitation products to equilibrium phases in U10Mo alloys

doi:https://doi.org/10.1016/j.scriptamat.2018.07.010

Title: Phase transformation of metastable discontinuous precipitation products to equilibrium phases in U10Mo alloys

Full Record
Other Related Research

Abstract

In this study, the discontinuous precipitation (DP) mechanism is prevalent in over 80 alloy systems. We report a new type of DP occurring along prior -UMo grain boundaries of an alloy of uranium with 10 wt% molybdenum (U10Mo) during annealing at 500°C, forming alternate lamellae of Mo-enriched -UMo and -U. During prolonged annealing, the metastable Mo-enriched -UMo lamellae gradually transform into a composite mixture of equilibrium -U ₂Mo embedded in Mo-depleted -UMo. Using high resolution scanning transmission electron microscopy and atom probe tomography, a comprehensive description of the structural and compositional changes of the metastable lamellar DP product to near-equilibrium phases is provided.

Authors:

^[1]; Kautz, Elizabeth J. ^[1]; Kovarik, Libor ^[1]; Jana, Saumyadeep ^[1]; Overman, Nicole ^[1]; Lavender, Curt A. ^[1];

^[1]

Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Publication Date:: 2018-07-20

Research Org.:: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1464644

Report Number(s):: PNNL-SA-134393
Journal ID: ISSN 1359-6462

DOE Contract Number:: AC05-76RL01830

Resource Type:: Journal Article

Journal Name:: Scripta Materialia

Additional Journal Information:: Journal Volume: 156; Journal Issue: C; Journal ID: ISSN 1359-6462

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE

Citation Formats


                    Devaraj, Arun, Kautz, Elizabeth J., Kovarik, Libor, Jana, Saumyadeep, Overman, Nicole, Lavender, Curt A., and Joshi, Vineet V. Phase transformation of metastable discontinuous precipitation products to equilibrium phases in U10Mo alloys.  United States: N. p., 2018. 
        Web.  doi:10.1016/j.scriptamat.2018.07.010.

Copy to clipboard


                    Devaraj, Arun, Kautz, Elizabeth J., Kovarik, Libor, Jana, Saumyadeep, Overman, Nicole, Lavender, Curt A., & Joshi, Vineet V. Phase transformation of metastable discontinuous precipitation products to equilibrium phases in U10Mo alloys.  United States.  https://doi.org/10.1016/j.scriptamat.2018.07.010

Copy to clipboard


                    Devaraj, Arun, Kautz, Elizabeth J., Kovarik, Libor, Jana, Saumyadeep, Overman, Nicole, Lavender, Curt A., and Joshi, Vineet V. Fri .  
        "Phase transformation of metastable discontinuous precipitation products to equilibrium phases in U10Mo alloys".  United States.  https://doi.org/10.1016/j.scriptamat.2018.07.010.

Copy to clipboard


                    
@article{osti_1464644,

  title        = {Phase transformation of metastable discontinuous precipitation products to equilibrium phases in U10Mo alloys},

  author       = {Devaraj, Arun and Kautz, Elizabeth J. and Kovarik, Libor and Jana, Saumyadeep and Overman, Nicole and Lavender, Curt A. and Joshi, Vineet V.},

  abstractNote = {In this study, the discontinuous precipitation (DP) mechanism is prevalent in over 80 alloy systems. We report a new type of DP occurring along prior -UMo grain boundaries of an alloy of uranium with 10 wt% molybdenum (U10Mo) during annealing at 500°C, forming alternate lamellae of Mo-enriched -UMo and -U. During prolonged annealing, the metastable Mo-enriched -UMo lamellae gradually transform into a composite mixture of equilibrium -U2Mo embedded in Mo-depleted -UMo. Using high resolution scanning transmission electron microscopy and atom probe tomography, a comprehensive description of the structural and compositional changes of the metastable lamellar DP product to near-equilibrium phases is provided.},

  doi          = {10.1016/j.scriptamat.2018.07.010},

  url          = {https://www.osti.gov/biblio/1464644},
  journal      = {Scripta Materialia},

  issn         = {1359-6462},

  number       = C,

  volume       = 156,

  place        = {United States},

  year         = {2018},

  month        = {7}

}

Copy to clipboard

Journal Article:

https://doi.org/10.1016/j.scriptamat.2018.07.010

Other availability

Find in Google Scholar

Search WorldCat to find libraries that may hold this journal

Save / Share:

Export Metadata

Save to My Library

Similar records in OSTI.GOV collections:

Discontinuous Precipitation in U-10 wt.%Mo Alloy: Reaction Kinetics, Effect of Prior gamma-UMo Microstructure, the Role of Grain-Boundary Misorientation, and the Effect of Ternary Alloying Addition

Journal Article Jana, Saumyadeep ; Overman, Nicole R. ; Devaraj, Arun ; ... - JOM. The Journal of the Minerals, Metals and Materials Society

Eutectoid transformation in U-10 wt.% Mo (U10Mo) alloy initiates through discontinuous precipitation (DP) resulting in the formation of a lamellar microstructure that consists of an a-U and Mo-enriched bcc ?-UMo phase along the prior ?-UMo grain boundaries. DP is the main mode of transformation at 500°C. However, continuous precipitation (CP) of ?’ U2Mo phase together with grain-boundary DP is observed at 400°C. The reaction kinetics are noted to be very sluggish at 400°C compared to 500°C. The degree of eutectoid transformation is related to the prior ?-UMo grain size, and a smaller average grain size leads to a larger amountmore »« less
https://doi.org/10.1007/s11837-019-03588-4
Grain boundary engineering to control the discontinuous precipitation in multicomponent U10Mo alloy

Journal Article Devaraj, Arun ; Kovarik, Libor ; Kautz, Elizabeth ; ... - Acta Materialia

Grain boundaries in metallic alloys often play a crucial role, not only in determining the mechanical properties or thermal stability of alloys, but also in dictating the phase transformation kinetics during thermomechanical processing. We demonstrate that locally stabilized structure and compositional segregation at grain boundaries—“grain boundary complexions”—in a complex multicomponent alloy can be modified to influence the kinetics of cellular transformation during subsequent thermomechanical processing. Using aberration-corrected scanning transmission electron microscopy and atom probe tomography analysis of a metallic nuclear fuel highly relevant to worldwide nuclear non-proliferation efforts —uranium-10 wt% molybdenum (U-10Mo) alloy, new evidence for the existence of grainmore »« less
https://doi.org/10.1016/j.actamat.2018.03.039
Grain boundary engineering to control the discontinuous precipitation in multicomponent U10Mo alloy

Journal Article Devaraj, Arun ; Kovarik, Libor ; Kautz, Elizabeth ; ... - Acta Materialia

Here, 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.more »« less
Cited by 6
https://doi.org/10.1016/j.actamat.2018.03.039

Full Text Available
Kinetics of cellular transformation and competing precipitation mechanisms during sub-eutectoid annealing of U10Mo alloys

Journal Article Jana, S. ; Devaraj, A. ; Kovarik, L. ; ... - Journal of Alloys and Compounds

Transformation kinetics of metastable body-centered cubic γ-UMo phase in U-10 wt.percent Mo alloy during annealing at sub-eutectoid temperatures of 500C and 400C has been determined as a function of time using detailed microstructural characterization by scanning electron microscopy, X-ray diffraction analysis, scanning transmission electron microscopy, and atom probe tomography. Based on the results, we found that the phase transformation is initiated by cellular transformation at both the temperatures, which results in formation of a lamellar microstructure along prior γ-UMo grain boundaries.
https://doi.org/10.1016/j.jallcom.2017.06.292
Eutectoid Transformation in U10Mo Alloy: Effect of Deformation History and Homogenization Heat Treatment

Technical Report Jana, Saumyadeep ; Schemer-Kohrn, Alan L. ; Overman, Nicole R. ; ...

In the United States, uranium 10 wt.% molybdenum (U10Mo) alloy has been selected as the nuclear fuel that will be used when transitioning research reactors and radioisotope production facilities from highly enriched uranium (>85% ²³⁵U) fuel to low-enriched uranium (<20% ²³⁵U) fuel. The fabrication steps for producing U10Mo fuel foil involve multiple hot-rolling/cold-rolling/intermediate annealing steps. The U10Mo alloy, which can retain the desirable high-temperature body-centered cubic γ-U (A2) structure at room temperature as a metastable phase for optimum in-reactor performance, goes through a eutectoid reaction below ~560°C and forms a-U as a reaction product, which is highly undesirable. Because themore »« less
https://doi.org/10.2172/1503687

Full Text Available

Similar Records