Mukesh Bachhav

Profile Information
Name
Dr. Mukesh Bachhav
Institution
Idaho National Laboratory
Position
Staff Scientist
Affiliation
INL
h-Index
ORCID
0000-0001-8104-6032
Expertise
APT
Publications:
"A novel approach to determine the local burnup in irradiated fuels using Atom Probe Tomography (APT)" Mukesh Bachhav, Jian Gan, Dennis Keiser, Jeffrey Giglio, Daniel Jadernas, Ann Leenaers, Sven Van den Berghe, Journal of Nuclear Materials Vol. 528 2020 Link
"Clustering and Radiation Induced Segregation in Neutron Irradiated Fe-(3-18)Cr Alloys" Mukesh Bachhav, Emmanuelle Marquis, G. Robert Odette, Microsc. Microanal. 21 Vol. 21 2016 581-582 Link
High chromium ferritic-martensitic (F-M) steels are one of the promising structural material classes for future nuclear power plants. These steels are designed to combine corrosion resistance, conferred by chromium, with low swelling, high resistance to irradiation damage as well as to retain adequate toughness and elevated-temperature strength during service [1]. However, the long-term use of these steels in intense neutron irradiation environments requires reliable predictions of the evolution of their microstructures and mechanical properties. Binary Fe-Cr alloys constitute a model system for high Cr ferritic/martensitic steels and have therefore generated lot of interest by allowing the systematic study on irradiation induced microstructural changes. In the present study, microstructural changes in neutron irradiated Fe-Cr binary alloys are investigated using atom probe tomography (APT). A series of six Fe-Cr alloys of nominal compositions 3, 6, 9, 12, 15, and 18 at.%Cr were irradiated at a neutron fluence (E>1 MeV) of 1.1 x 1021 n/cm2 at 563 ± 15K and to a damage level of 1.82 displacements per atom (dpa). Solute distributions revealed a' precipitation for alloys containing more than 9at.%Cr (Figure 1). Both the Cr concentration dependence of a' precipitation and the measured matrix compositions are in agreement with the recently published Fe-Cr phase diagrams [2]. An irradiation-accelerated precipitation process is strongly suggested for a' precipitation. Along with homogenously distributed Cr-enriched clusters of the a' phase, few clusters involving Si, P, Ni, and Cr, are observed in the matrix [3]. For Fe-6, 9, 12 at.%Cr, Si and Cr are found segregated to dislocation loops and information pertaining to number density, size, and habit plane were analyzed for Fe-6at.%Cr alloy[4]. Grain boundary chemistry for Fe-Cr alloys are quantitatively compared between the as-received and the neutron irradiated alloys. Zones depleted of a' clusters and Si are found at the interfaces of carbide and nitride precipitates and along grain boundaries in the vicinity of these precipitates. To study stability of clusters and observed features in irradiated samples, annealing is carried out at high temperatures. The results are discussed in the context of equilibrium segregation, radiation-enhanced diffusion, and/or radiation induced segregation.
"Interpreting the Presence of an Additional Oxide Layer in Analysis of Metal Oxides−Metal Interfaces in Atom Probe Tomography" Mukesh Bachhav, Gorakh Pawar, Yan Dong, Emmanuelle Marquis, Journal of Physical Chemistry Vol. 123 2018 1313-1319 Link
"Irradiation-Induced Nb redistribution of ZrNb alloy: an APT study" Zefeng Yu, Adrien Couet, Mukesh Bachhav, Journal of Nuclear Materials Vol. 516 2019 Link
We have investigated proton irradiation induced Nb redistribution in Zr-xNb alloy (x = 0.4, 0.5, 1.0) by using scanning transmission electron microscopy (STEM) and atom probe tomography (APT). We have found by STEM that 2MeV proton irradiation at 350°C induces precipitation of Nb-rich needle-like particles in the Zr matrix. Initially without irradiation effect, the Zr matrix only contains βNb and Laves phase native precipitates. After irradiation, in addition to the needle-like particles, we have also found by APT that Fe- and Nb-rich nanoclusters (less than 20 nm diamter) are present in the Zr matrix for Zr-0.5Nb, 1000°C annealed Zr-0.5Nb and Zr-1.0Nb. Despite different irradiation dose level, the total Nb content in the entire APT tip for all the samples ranges from 0.24 – 0.40 at. %, which is below the maximum solubility limit of 0.6 at. % Nb in Zr solid solution. After cluster removal from the Zr matrix of the irradiated samples, Nb concentration in the Zr solid solution is shown to significantly decrease with irradiation dose, which is suspected to be responsible for the improved corrosion resistance of ZrNb alloy in the reactor environment at high burnup.
"Measurement of grain boundary strength of Inconel X-750 superalloy using in-situ micro-tensile testing techniques in FIB/SEM system" Yachun Wang, Xiang Liu, Daniel Murray, Fei Teng, Wen Jiang, Mukesh Bachhav, Laura Hawkins, Emmanuel Perez, Cheng Sun, Xianming Bai, Jie Lian, Colin Judge, John Jackson, Robert Carter, Lingfeng He, Materials Science & Engineering Vol. 849 2022
"Microstructural changes and their effect on hardening in neutron irradiated Fe-Cr alloys" Dhriti Bhattacharyya, Takuya Yamamoto, Peter Wells, Emmanuelle Marquis, Mukesh Bachhav, Yuan Wu , Joel Davis, Alan Xu, G. Robert Odette, Journal of Nuclear Materials Vol. 519 2019 274-286 Link
"Microstructural changes in a neutron-irradiated Fe–15 at.%Cr alloy" Mukesh Bachhav, Emmanuelle Marquis, G. Robert Odette, Journal of Nuclear Materials Vol. 454 2014 381-386 Link
Microstructural changes in a Fe–15 at.%Cr model alloy neutron irradiated to 1.82 dpa at 290 °C were characterized by atom probe tomography. Homogenously distributed a' precipitates as well as fewer clusters containing Si, P, Ni, and Cr, were observed in the matrix. Grain boundary analyses before and after irradiation revealed segregation of Cr, with W-shape concentration profiles developing in the vicinity of grain boundary carbide and nitride particles. After irradiation, impurities such as C, Si and P were segregated to the grain boundaries. Zones depleted of a' clusters, and Si were found at the interfaces of carbide and nitride precipitates and along grain boundaries in the vicinity of these precipitates.
"Microstructural changes in a neutron-irradiated Fe–6 at.%Cr alloy" Mukesh Bachhav, Emmanuelle Marquis, G. Robert Odette, Lan Yao, Journal of Nuclear Materials Vol. 453 2014 334-339 Link
The microstructural and chemical changes in a Fe–6 at.%Cr binary model alloy neutron irradiated to 1.82 dpa at 290 °C were investigated using atom probe tomography. After irradiation, Si and Cr are found segregated to dislocation loops, which were analyzed in terms of number density, size, and habit plane. Grain boundary chemistry was quantitatively compared between the as-received and the neutron irradiated alloys. The results are discussed in the context of equilibrium segregation, radiation-enhanced diffusion, and/or radiation induced segregation.
"Microstructure and Fission Product Distribution Examination in the UCO kernel of TRISO Fuel Particles" Isabella van Rooyen, Yong Yang, Terry Holesinger, Mukesh Bachhav, OSTI.gov, Conf Proceedings Vol. 2018 Link
"On a' precipitate composition in thermally annealed and neutron-irradiated Fe- 9-18Cr alloys" Mukesh Bachhav, Emmanuelle Marquis, G. Robert Odette, Peter Wells, Takuya Yamamoto, Elaina Reese, Journal of Nuclear Materials Vol. 500 2018 192-198 Link
Ferritic-martensitic steels are leading candidates for many nuclear energy applications. However, formation of nanoscale a' precipitates during thermal aging at temperatures above 450?°C, or during neutron irradiation at lower temperatures, makes these Fe-Cr steels susceptible to embrittlement. To complement the existing literature, a series of Fe-9 to 18 Cr alloys were neutron-irradiated at temperatures between 320 and 455?°C up to doses of 20 dpa. In addition, post-irradiation annealing treatments at 500 and 600?°C were performed on a neutron-irradiated Fe-18 Cr alloy to validate the a-a' phase boundary. The microstructures were characterized using atom probe tomography and the results were analyzed in light of the existing literature. Under neutron irradiation and thermal annealing, the measured a' concentrations ranged from ~81 to 96?at.% Cr, as influenced by temperature, precipitate size, technique artifacts, and, possibly, cascade ballistic mixing.
"STEM-EDS/EELS and APT characterization of ZrN coatings on UMo fuel kernels" Lingfeng He, Mukesh Bachhav, Dennis Keiser, Emmanuel Perez, Brandon Miller, Jian Gan, Ann Leenaers, Sven Van den Berghe, Journal of Nuclear Materials Vol. 511 2018 174-182 Link
"α' precipitation in neutron-irradiated Fe-Cr alloys" Mukesh Bachhav, G. Robert Odette, Emmanuelle Marquis, Scripta Materialia Vol. 74 2014 48-51 Link
A series of model Fe–Cr alloys containing 3–18 at.% Cr was neutron irradiated at a nominal temperature of 563 K to 1.82 dpa. Solute distributions were analyzed by atom probe tomography, which revealed a' precipitation for alloys containing more than 9 at.% Cr. Both the Cr concentration dependence of a' precipitation and the measured matrix compositions are in agreement with the recently published Fe–Cr phase diagrams. An irradiation-accelerated precipitation process is strongly suggested.
Presentations:
"Behavior of Fe-Cr Alloys under Ion or neutron Irradiation" Mukesh Bachhav, Emmanuelle Marquis, TMS 2014 February 16-20, (2014)
"Recent observations from the microstructural characterization of irradiated U-Mo fuels using advanced techniques" Dennis Keiser, Brandon Miller, Jian Gan, Lingfeng He, Daniel Jadernas, Mukesh Bachhav, NUMAT 2018 October 15-18, (2018)