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Vogel F, Ngai S, Smith C, Holler R, Weinberger C, Wanderka N, Thompson G. Carbide and nitride phase characterization in a transition metal carbo-nitride using x-ray spectroscopy and atom probe tomography. Micron 2019; 122:32-40. [DOI: 10.1016/j.micron.2019.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 10/26/2022]
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Verma A, Wanderka N, Singh JB, Kumar B, Banhart J. Statistical analysis of composition fluctuations and short-range order in stoichiometric Ni-Cr-Mo alloys. Ultramicroscopy 2013; 132:227-32. [PMID: 23588067 DOI: 10.1016/j.ultramic.2013.02.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 02/01/2013] [Accepted: 02/28/2013] [Indexed: 10/27/2022]
Abstract
In the solution treated state Ni-Cr-Mo based alloys exhibit short-range order characterized by the appearance of diffuse intensity spots in electron diffraction patterns at {1 ½ 0} positions. This short-range order appears due to of the formation of chemical heterogeneities. In the present work we report on the investigation of short-range order in Ni-33 at% Cr and Ni-16.7 at% Cr-16.7 at% Mo alloys using transmission electron microscopy. Chemical heterogeneities and their sizes are analyzed by statistical methods applied to three-dimensional atom probe data obtained on the same alloys. The obtained chemical heterogeneities are correlated to regions of short-range order in Ni-33 at% Cr and Ni-16.7 at% Cr-16.7 at% Mo alloys.
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Affiliation(s)
- A Verma
- Helmholtz-Zentrum Berlin für Materialien und Energie, Institut für Angewandte Materialforschung, Hahn-Meitner-Platz, 1 D-14109 Berlin, Germany; Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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Timpel M, Wanderka N, Schlesiger R, Yamamoto T, Isheim D, Schmitz G, Matsumura S, Banhart J. Sr-Al-Si co-segregated regions in eutectic Si phase of Sr-modified Al-10Si alloy. Ultramicroscopy 2013; 132:216-21. [PMID: 23298536 DOI: 10.1016/j.ultramic.2012.10.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 09/30/2012] [Accepted: 10/20/2012] [Indexed: 11/16/2022]
Abstract
The addition of 200 ppm strontium to an Al-10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr-Al-Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of "impurity induced twinning".
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Affiliation(s)
- M Timpel
- Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
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Manzoni A, Daoud H, Völkl R, Glatzel U, Wanderka N. Phase separation in equiatomic AlCoCrFeNi high-entropy alloy. Ultramicroscopy 2012; 132:212-5. [PMID: 23352803 DOI: 10.1016/j.ultramic.2012.12.015] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 10/18/2012] [Accepted: 12/03/2012] [Indexed: 10/27/2022]
Abstract
The microstructure of the as-cast AlCoCrFeNi high entropy alloy has been investigated by transmission electron microscopy and atom probe tomography. The alloy shows a very pronounced microstructure with clearly distinguishable dendrites and interdendrites. In both regions a separation into an Al-Ni rich matrix and Cr-Fe-rich precipitates can be observed. Moreover, fluctuations of single elements within the Cr-Fe rich phase have been singled out by three dimensional atom probe measurements. The results of investigations are discussed in terms of spinodal decomposition of the alloying elements inside the Cr-Fe-rich precipitates.
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Affiliation(s)
- A Manzoni
- Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin, Germany.
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Timpel M, Wanderka N, Vinod Kumar G, Banhart J. Microstructural investigation of Sr-modified Al–15wt%Si alloys in the range from micrometer to atomic scale. Ultramicroscopy 2011; 111:695-700. [DOI: 10.1016/j.ultramic.2010.12.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 12/02/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
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Wanderka N, Lazarev N, Chang CST, Banhart J. Analysis of clustering in Al–Mg–Si alloy by density spectrum analysis of atom probe data. Ultramicroscopy 2011; 111:701-5. [DOI: 10.1016/j.ultramic.2010.11.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 11/01/2010] [Accepted: 11/14/2010] [Indexed: 10/18/2022]
Affiliation(s)
- N Wanderka
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin, Germany.
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Singh S, Wanderka N, Kiefer K, Siemensmeyer K, Banhart J. Effect of decomposition of the Cr–Fe–Co rich phase of AlCoCrCuFeNi high entropy alloy on magnetic properties. Ultramicroscopy 2011; 111:619-22. [DOI: 10.1016/j.ultramic.2010.12.001] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Revised: 11/29/2010] [Accepted: 12/02/2010] [Indexed: 11/29/2022]
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Mousa M, Wanderka N, Timpel M, Singh S, Krüger M, Heilmaier M, Banhart J. Modification of Mo-Si alloy microstructure by small additions of Zr. Ultramicroscopy 2011; 111:706-10. [PMID: 21215523 DOI: 10.1016/j.ultramic.2010.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 11/16/2022]
Abstract
Molybdenum and its alloys are potential materials for high-temperature applications. However, molybdenum is susceptible to embrittlement because of oxygen segregation at the grain boundaries. In order to alleviate the embrittlement small amounts of zirconium were alloyed to a solid solution of Mo-1.5Si alloy. Two Mo-based alloys, namely Mo-1.5Si and Mo-1.5Si-1Zr, were investigated by the complementary high-resolution methods transmission electron microscopy and atom probe tomography. The Mo-1.5Si alloy shows a polycrystalline structure with two silicon-rich intermetallic phases Mo(5)Si(3) and Mo(3)Si located at the grain boundaries and within the grains. In addition, small clusters with up to 10 at% Si were found within the molybdenum solid solution. Addition of a small amount of zirconium to Mo-1.5Si leads to the formation of two intermetallic phases Mo(2)Zr and MoZr(2), which are located at the grain boundaries as well as within the interior of the grain. Transmission electron microscopy shows that small spherical Mo-Zr-rich precipitates (<10nm) decorate the grain boundaries. The stoichiometry of the small precipitates was identified as Mo(2)Zr by atom probe tomography. No Si-enriched small precipitates were detected in the Mo-1.5Si-1Zr alloy. It is concluded that the presence of zirconium hinders their formation.
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Affiliation(s)
- M Mousa
- Mu'tah University, Department of Physics, Al-Karak, Jordan
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Mikhailovskij I, Wanderka N, Storizhko V, Ksenofontov V, Mazilova T. A new approach for explanation of specimen rupture under high electric field. Ultramicroscopy 2009; 109:480-5. [DOI: 10.1016/j.ultramic.2008.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 11/28/2008] [Accepted: 12/03/2008] [Indexed: 10/21/2022]
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Chang C, Wieler I, Wanderka N, Banhart J. Positive effect of natural pre-ageing on precipitation hardening in Al–0.44 at% Mg–0.38 at% Si alloy. Ultramicroscopy 2009; 109:585-92. [DOI: 10.1016/j.ultramic.2008.12.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 11/27/2008] [Accepted: 12/03/2008] [Indexed: 11/17/2022]
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Mukherji D, Lackner J, Wanderka N, Kardjilov N, Näth O, Jäger S, Schmitz F, Rösler J. Coating of meso-porous metallic membranes with oriented channel-like fine pores by pulsed laser deposition. Nanotechnology 2008; 19:065706. [PMID: 21730712 DOI: 10.1088/0957-4484/19/6/065706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
There is increasing demand to functionalize meso- and nanoporous materials by coating and make the porous substrate biocompatible or environmentally friendly. However, coating on a meso-porous substrate poses great challenges, especially if the pore aspect ratio is high. We adopted the pulsed laser deposition (PLD) method to coat Ni(3)Al-based meso-porous membranes, which were fabricated from a single-crystal Ni-based superalloy by a unique selective phase dissolution technique. These membranes were about 250 µm thick and had channel-like pores (∼200 nm wide) with very high aspect ratio. Two different coating materials, i.e. diamond-like carbon (DLC) and titanium, were used to coat these membranes. High energy C or Ti ions, produced in the plasma plume by the PLD process, penetrated the channel-like pores and deposited coatings on the pore walls deep inside the membrane. The thickness and the quality of coatings on the pore walls were examined using the dual-beam system. The coating thickness, of the order of 50 nm, was adherent to the pore walls and was quite uniform at different depths. The carbon and the Ti deposition behaved quite similarly. The preliminary experiments showed that the PLD is an adequate method for coating fine open cavities of complex geometry. Simulations based on stopping and the range of ions in matter (SRIM) calculations helped in understanding the deposition processes on pore walls at great depths.
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Affiliation(s)
- D Mukherji
- Technische Universität Braunschweig, IfW, Langer Kamp 8, D-38106 Braunschweig, Germany
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Wanderka N, Bakai A, Abromeit C, Isheim D, Seidman DN. Effects of 10MeV electron irradiation at high temperature of a Ni–Mo-based Hastelloy. Ultramicroscopy 2007; 107:786-90. [PMID: 17403580 DOI: 10.1016/j.ultramic.2007.02.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A Hastelloy alloy was irradiated with 10 MeV electrons at 650 degrees C for 700 h to a total dose of 2 x 10(-3) displacements per atom (dpa). The microstructure of irradiated and non-irradiated specimens of this alloy were investigated by transmission electron microscopy (TEM). The non-irradiated specimens were analyzed by 3-D atom probe tomography (APT) in a local-electrode atom-probe (LEAP). TEM analysis before the irradiation detects small precipitates with a mean diameter of 22 nm, which are coherent with the FCC matrix. The number density of these precipitates is approximately 7 x 10(18) m(-3). Electron diffraction patterns from these precipitates exhibit superlattice reflections corresponding to the L1(2) ordered structure. The chemical composition of the precipitates, as measured by APT, is around 75 at% Ni with additions of Al, Ti and Mo. After electron irradiation, small precipitates with an irregular morphology are observed. The number density of these new precipitates about 10(20) m(-3) is greater than that of the L1(2) ordered precipitates before irradiation. The L1(2) superlattice reflections disappear completely, instead diffuse diffraction spots are observed at 1(1/2)0(FCC), which is attributed to compositional short-range order (SRO). The results are discussed with respect to the influence of the electron irradiation on the morphology and structure of the ordered precipitates.
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Affiliation(s)
- N Wanderka
- Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin, Germany.
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Kindrachuk V, Wanderka N, Banhart J, Mukherji D, Del Genovese D, Rösler J. Microchemical characterization of phases in Inconel 706 and DT 706 alloys after aging. SURF INTERFACE ANAL 2007. [DOI: 10.1002/sia.2515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Leitner H, Clemens H, Höring S, Wanderka N, Banhart J, Staron P, Jamnig B. Characterisation of precipitates in a stainless maraging steel by three-dimensional atom probe and small-angle neutron scattering. ACTA ACUST UNITED AC 2004. [DOI: 10.3139/146.018001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wanderka N, Naundorf V, Banhart J, Mukherji D, Genovesse DD, Rösler J. Microstructural characterization of Inconel 706 alloy. SURF INTERFACE ANAL 2004. [DOI: 10.1002/sia.1696] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Dieter S, Pyzalla A, Bauer A, Schell N, McCord J, Seemann K, Wanderka N, Reimers W. Correlation between magnetic properties of CoFe single and CoFe/SiO2multi-layer thin films and their microstructure, texture and internal stress state. ACTA ACUST UNITED AC 2004. [DOI: 10.3139/146.017930] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Low-temperature field evaporation of the [111] steps on a W(211) surface was investigated by field ion microscopy (FIM). The atoms at the (112)[1;1;1] kink site are anomalously stable against field evaporation. This effect results in non-kinkwise field evaporation near the kink of this type. The non-kinkwise field evaporating steps [211]<111> usually produce the reconstructed atomic chain with double-space arranged adatoms. The experimental results reveal atomic relaxation effects at steps and kinks. The normal to surface differential relaxation of the kink-site atoms was estimated by the geometrical method of indirect magnification and by simulation of the FIM image.
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Affiliation(s)
- I M Mikhailovskij
- Department of Solid State Physics, Kharkov Institute of Physics and Technology, Academicheskaja 1, 61108, Kharkov, Ukraine.
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Wanderka N, Czubayko U, Naundorf V, Ivchenko VA, Uimin MA, Wollenberger H. Characterization of nanoscaled heterogeneities in mechanically alloyed and compacted CuFe. Ultramicroscopy 2001; 89:189-94. [PMID: 11770746 DOI: 10.1016/s0304-3991(01)00104-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Cu80Fe20 and Cu50Fe50 were mechanically alloyed from the pure elements by ball milling for 36 h. The alloy powder was compacted into tablets at room temperature by applying a pressure of 5 GPa. Characterization of the Cu80Fe20) and Cu50Fe50 alloys was carried out by high-resolution transmission electron microscopy (HREM), atom probe field ion microscopy and three-dimensional atom probe (3DAP). The grain size of the nanocrystalline microstructure of the ball-milled alloys observed with HREM varies between 3 and 50 nm. Atom probe and 3DAP measurements indicate that the as-prepared state is a highly supersaturated alloy, in which the individual nanocrystals have largely varying composition. Fe concentration in Cu was found to range from about 8 to 50 at%. It is concluded that by ball milling and compacting an alloy is produced which on a nanometer scale is heterogeneous with respect to morphology and composition.
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Rüsing J, Naundorf V, Wanderka N, Wollenberger H. Analysis of the decomposition of Cu–Ni and Fe–Ni alloys at lower temperatures by atom probe. Ultramicroscopy 1998. [DOI: 10.1016/s0304-3991(97)00166-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Camus E, Abromeit C, Bourdeau F, Wanderka N, Wollenberger H. Evolution of long-range order and composition for radiation-induced precipitate dissolution. Phys Rev B Condens Matter 1996; 54:3142-3150. [PMID: 9986213 DOI: 10.1103/physrevb.54.3142] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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