The concept of the new small-angle scattering instrument SANS-1 at the FRM-II

Gilles, Ralph; Ostermann, Andreas; Schanzer, Christian; Krimmer, B.; Petry, W.

doi:10.1016/j.physb.2006.05.403

Cited by 24 publications

(20 citation statements)

References 1 publication

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“…Since the determination of the γ particle size distribution and γ volume fraction of the complex tridisperse γ structure is difficult by electron microscopy techniques, in-situ and ex-situ heat treatments were performed at the small-angle neutron scattering facility SANS-1 at the Heinz-Maier-Leibnitz Center of the TU München (FRM II) [20]. For the SANS measurements, discs with a diameter of 15 mm were cut from recrystallized bars in fully heat-treated conditions, which were ground to achieve parallel surfaces and a thickness of 1 mm.…”

Section: Methodsmentioning

confidence: 99%

Enhancing the High-Temperature Strength of a Co-Base Superalloy by Optimizing the γ/γ′ Microstructure

Hausmann

Solís

Freund

et al. 2020

Metals

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Compositionally complex polycrystalline γ/γ′ CoNi-base superalloys, such as CoWAlloy2 (Co41-Ni32-Cr12-Al9-W5-Ti0.3-Ta0.2-Si0.4-Hf0.1-C-B-Zr) are interesting candidates for new high-temperature materials. To maximize their high-temperature strength, the γ/γ′ microstructure has to be optimized by adjusting the multi-step heat treatments. Various microstructures after different heat treatments were analyzed by scanning and transmission electron microscopy and especially in-situ small-angle neutron scattering during heat treatment experiments. The corresponding mechanical properties were determined by compression tests and hardness measurements. From this, an optimum γ′ precipitate size was determined that is adjusted mainly in the first precipitation heat treatment step. This is discussed on the basis of the theory of shearing of γ′ precipitates by weak and strong pair-couplings of dislocations. A second age hardening step leads to a further increase in the γ′ volume fraction above 70% and the formation of tertiary γ′ precipitates in the γ channels, resulting in an increased hardness and yield strength. A comparison between two different three-step heat treatments revealed an increase in strength of 75 MPa for the optimized heat treatment.

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Section: Methodsmentioning

confidence: 99%

Enhancing the High-Temperature Strength of a Co-Base Superalloy by Optimizing the γ/γ′ Microstructure

Hausmann

Solís

Freund

et al. 2020

Metals

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“…Leibnitz Zentrum (MLZ) in Garching, Germany (Gilles et al, 2006;Mü hlbauer et al, 2016;Heinemann & Mü hlbauer, 2015). Measurements were performed with a neutron wavelength of 6 Å and a sample-to-detector distance of 8 m (the same value was chosen for the collimation) to cover a medium q range of 0.068-0.934 nm À1 [q = (4/) sin, where is half the scattering angle and is the wavelength of the incident beam].…”

Section: Methodsmentioning

confidence: 99%

Li-ion half-cells studied operando during cycling by small-angle neutron scattering

et al. 2020

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Small-angle neutron scattering (SANS) was recently applied to the in situ and operando study of the charge/discharge process in Li-ion battery full-cells based on a pouch cell design. Here, this work is continued in a half-cell with a graphite electrode cycled versus a metallic lithium counter electrode, in a study conducted on the SANS-1 instrument of the neutron source FRM II at the Heinz Maier-Leibnitz Zentrum in Garching, Germany. It is confirmed that the SANS integrated intensity signal varies as a function of graphite lithiation, and this variation can be explained by changes in the squared difference in scattering length density between graphite and the electrolyte. The scattering contrast change upon graphite lithiation/delithiation calculated from a multi-phase neutron scattering model is in good agreement with the experimentally measured values. Due to the finite coherence length, the observed SANS contrast, which mostly stems from scattering between the (lithiated) graphite and the electrolyte phase, contains local information on the mesoscopic scale, which allows the development of lithiated phases in the graphite to be followed. The shape of the SANS signal curve can be explained by a core-shell model with step-wise (de)lithiation from the surface. Here, for the first time, X-ray diffraction, SANS and theory are combined to give a full picture of graphite lithiation in a half-cell. The goal of this contribution is to confirm the correlation between the integrated SANS data obtained during operando measurements of an Li-ion half-cell and the electrochemical processes of lithiation/delithiation in micro-scaled graphite particles. For a deeper understanding of this correlation, modelling and experimental data for SANS and results from X-ray diffraction were taken into account. research papers J. Appl. Cryst. (2020). 53, 210-221 Johannes Hattendorff et al. SANS operando study of Li-ion half-cells 211 research papers 212 Johannes Hattendorff et al. SANS operando study of Li-ion half-cells J. Appl. Cryst. (2020). 53, 210-221 Figure 2An operando X-ray diffractogram recorded from the Li/graphite half-cell cycled at C/5, showing the presence of well defined lithiation stages, which indicates good homogeneity across the electrode. J. Appl. Cryst. (2020). 53, 210-221 Johannes Hattendorff et al. SANS operando study of Li-ion half-cells 219 Figure 9An illustration of the calculation mesh and the coherence volumes centred at each mesh element k, (a) for small particles and (b) for a large particle with two phases, e.g. active material and electrolyte or solvent. One square is of the order of 30 nm.

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“…Single curved neutron guides have a disadvantage for SANS instruments at small wavelengths. Due to the different reflection probability of the inner and outer surface of the neutron guide, an intensity and divergence inhomogeneity results at the detector (Gilles et al, 2006). As a consequence, isotropic patterns on the detector can not be effectively summed up by radial averaging.…”

Section: Simulations Of the S-shaped Neutron Guidementioning

confidence: 99%

“…More important is the symmetry achieved in the divergence profile which is not present in single curved neutron guides for small wavelengths (Gilles et al, 2006) except when small apertures are installed in the collimation part. To implement further instruments in the neutron guide hall, the vertical S-shaped guide has in the second part of the S-shape an additional horizontal curvature with a radius R = 2100 m and a length of 12.2 m. All subsequent parts of the instrument lie in a straight line.…”

Section: Simulations Of the S-shaped Neutron Guidementioning

confidence: 99%

Monte Carlo simulations of the new small-angle neutron scattering instrument SANS-1 at the Heinz Maier-Leibnitz Forschungsneutronenquelle

2007

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A new small-angle scattering instrument SANS-1 will be installed on beamline NL 4a at the Heinz Maier-Leibnitz Forschungsneutronenquelle (FRM II). It is a joint venture between the Technische Universitä t Mü nchen and the Geesthacht Neutron Facility (GENF). SANS-1 has been optimized to be one of the most intense and versatile small-angle scattering instruments within the boundaries of available space and interaction with neighbouring instruments. Using the program McStas, the dimensions and the features of the different optical components were investigated and compared for the final selection. A vertical Sshaped neutron guide, a tower with two possible selectors, one for medium resolution at high intensity and one for high resolution, and two optimized transmission polarizers are the main advantages of SANS-1 compared with traditional instruments at other facilities.

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The concept of the new small-angle scattering instrument SANS-1 at the FRM-II

Cited by 24 publications

References 1 publication

Enhancing the High-Temperature Strength of a Co-Base Superalloy by Optimizing the γ/γ′ Microstructure

Enhancing the High-Temperature Strength of a Co-Base Superalloy by Optimizing the γ/γ′ Microstructure

Li-ion half-cells studied operando during cycling by small-angle neutron scattering

Monte Carlo simulations of the new small-angle neutron scattering instrument SANS-1 at the Heinz Maier-Leibnitz Forschungsneutronenquelle

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