Experimental investigation of the ordering pathway in a Ni-33 at.%Cr alloy

Gwalani, Bharat; Alam, Talukder; Miller, Cody; Rojhirunsakool, Tanaporn; Kim, Y. S.; Kim, S. S.; Kaufman, Michael J.; Ren, Yang; Banerjee, Rajarshi

doi:10.1016/j.actamat.2016.06.014

Cited by 48 publications

(26 citation statements)

References 26 publications

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“…The Fit-2D software was used to radially integrate the 2D diffraction data to produce 1D intensity vs. two-theta (2θ) plots. Further details about the experimental procedure can be found elsewhere [32]. The resulting 1D diffraction data were analyzed using the Pawley method [33], as embodied in the TOPAS software package (Bruker), to obtain accurate measurements of the lattice parameters for the two phases as a function of temperature.…”

Section: Methodsmentioning

confidence: 99%

Cu assisted stabilization and nucleation of L12 precipitates in Al0.3CuFeCrNi2 fcc-based high entropy alloy

et al. 2017

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A detailed investigation of precipitation of the ordered L1 2 (γ′) phase in a Al 0.3 CrCuFeNi 2 high entropy alloy (HEA), more generally referred to as a complex concentrated alloy (CCA), reveals the role of copper (Cu) on stabilization and precipitation of the ordered L1 2 (γ′) phase. Detailed characterization via coupling of scanning and transmission electron microscopy, and atom probe tomography revealed novel insights into Cu clustering within the face-centered cubic matrix of this HEA, leading to heterogeneous nucleation sites for the γ′ precipitates. The subsequent partitioning of Cu into the γ′ precipitates indicates their stabilization is due to Cu addition. The γ′ order-disorder transition temperature was determined to be ~930 o C in this alloy, based on synchrotron diffraction experiments, involving in situ annealing. The growth and high temperature stability of the γ′ precipitates was also confirmed via systematic scanning electron microscopy investigations of samples annealed at temperatures in the range of 700 -900°C. The role of Cu revealed by this study can be employed in the design of precipitation strengthened HEAs, as well as in a more general sense applied to other types of superalloys, with the objective of potentially enhancing their mechanical properties at room and elevated temperatures.

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Section: Methodsmentioning

confidence: 99%

Cu assisted stabilization and nucleation of L12 precipitates in Al0.3CuFeCrNi2 fcc-based high entropy alloy

et al. 2017

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“…Atom probe tomography (APT) is a novel microscopy analysis technique that is capable to provide three dimensional composition distributions at sub‐nanometer resolution . The recent introduction of modern laser pulsing systems has expanded materials systems that can be studied by APT from primarily metals to semiconductors, inorganic glasses, and ceramics materials . There exist rich microstructure evolutions in glass materials in the nanometer scale, such as phase separation and nucleation behaviors, where APT can provide direct local compositional information that is challenging to obtain using standard microscopy methods such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM).…”

Section: Introductionmentioning

confidence: 99%

Effects of optical dopants and laser wavelength on atom probe tomography analyses of borosilicate glasses

Schreiber

Neeway

et al. 2017

J Am Ceram Soc

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Atom probe tomography (APT) is a novel analytical microscopy method that provides three dimensional elemental mapping with sub-nanometer spatial resolution and has only recently been applied to insulating glass and ceramic samples. In this paper, we have studied the influence of the optical absorption in glass samples on APT characterization by introducing different transition metal optical dopants to a model borosilicate nuclear waste glass. A systematic comparison is presented of the glass optical properties and the resulting APT data quality in terms of compositional accuracy and the mass spectra quality for two APT systems: one with a green laser (532 nm, LEAP 3000X HR) and one with a UV laser (355 nm, LEAP 4000X HR). These data were also compared to the study of a more complex borosilicate glass (SON68). The results show that the analysis data quality, particularly the compositional accuracy and sample yield, was clearly linked to optical absorption when using a green laser, while for the UV laser optical doping aided in improving data yield but did not have a significant effect on compositional accuracy. Comparisons of data between the LEAP systems suggest that the smaller laser spot size of the LEAP 4000X HR played a more critical role for optimum performance than the optical dopants themselves. The smaller spot size resulted in more accurate composition measurements due to a reduced background level independent of the material's optical properties. K E Y W O R D Satom probe tomography, borosilicate glass, microscopy, nuclear waste glasses, optical properties, rare earth oxide, transition metal oxide

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“…Given that model alloys tend to develop LRO readily (see for example ref. [3]), a piece of model alloy with demonstrated LRO history [20] was obtained for this program from one of the authors, Dr. S.S. Kim of KAERI, Korea. The Ni-33Cr plate was made by vacuum induction melting followed by hot rolling at 1200C, solution annealing at 1050C for 1 h and water quenching.…”

Section: Model Ni-33cr Alloymentioning

confidence: 99%

“…The TEM examination matrix is shown in Table 8. In addition to the irradiated alloys, the model alloy Ni-33Cr aged for 2,000h at 475ºC with LRO confirmed to occur [20] was included as well as an Alloy 690 specimen (commercial heat) that was aged alongside the model alloy.…”

Section: Tem Of Irradiated Alloy 690 Specimensmentioning

confidence: 99%

Effect of thermal aging and irradiation on microstructure and crack growth response of Alloy 690

Alexandreanu¹,

Chen²,

Zhang³

et al. 2021

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Nickel-base Alloy 690 and the associated weld Alloys 52 and 152 are typically used for nozzle penetrations in replacement heads for pressurized water reactor (PWR) vessels, because of their excellent overall resistance to general corrosion and environmental degradation, primarily stress corrosion cracking (SCC). However, many of the existing PWRs reactors are expected to operate for 40-80 years. Likewise, advanced water-cooled small modular reactors (SMRs) will use Ni-Cr alloys and are expected to receive initial operating licenses for 60 years. Hence, the thermal stability of Ni-Cr alloys is a potential concern for the long-term performance of both existing and advanced nuclear plants, and possibly spent fuel storage containers. The objective of this research is to understand the microstructural changes occurring in high-Cr, Ni-based Alloy 690 during long time exposure to the reactor operating temperatures, and the effect of these changes on the service performance. One area of particular concern is the potential for long range ordering (LRO), i.e. formation of the intermetallic Ni2Cr phase under prolonged exposure to reactor temperatures and/or irradiation, which can increase strength, decrease ductility, and cause dimensional changes or lead to in-service embrittlement of components made with these alloys. Hence, this research focused on the microstructural evolution and the SCC response of Alloy 690 under accelerated thermal aging and irradiation conditions. The materials studied involved Alloy 690 from two sources: (i) Alloy 690 plate from an Alloy 152 dissimilar metal weld (DMW) joining the Alloy 690 plate to Alloy 533 LAS, aged at three different temperatures (370C, 400C and 450C) for up to 75,000h (equivalent to 60 years of service), and (ii) specimens neutron-irradiated in the BOR-60 reactor up to 40 dpa. For aged Alloy 690 specimens, hardness was found to increase with aging time, however, the microstructural characterization by means of synchrotron X-ray did not find evidence of LRO. The microstructural characterization of neutron-irradiated specimens by TEM found no evidence of LRO either. Testing in a primary water environment of Alloy 690 specimens aged to a 60year service equivalent revealed a fatigue and corrosion fatigue crack growth responses similar to those measured on the un-aged alloy. The SCC CGR response was also low. Overall, the two Alloy 690 heats investigated in this work, aged up to 60-year service equivalents or exposed to neutron irradiation up to 40 dpa, did not exhibit a deterioration in microstructure or performance.

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Experimental investigation of the ordering pathway in a Ni-33 at.%Cr alloy

Cited by 48 publications

References 26 publications

Cu assisted stabilization and nucleation of L12 precipitates in Al0.3CuFeCrNi2 fcc-based high entropy alloy

Cu assisted stabilization and nucleation of L12 precipitates in Al0.3CuFeCrNi2 fcc-based high entropy alloy

Effects of optical dopants and laser wavelength on atom probe tomography analyses of borosilicate glasses

Effect of thermal aging and irradiation on microstructure and crack growth response of Alloy 690

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