Effect of Cu On Microstructural Evolution of Nanocrystalline Soft and Hard Magnetic Materials

1999 ◽  
Vol 577 ◽  
Author(s):  
K. Hono ◽  
D. H. Ping ◽  
S. Hirosawa
Keyword(s):  
Amorphous Alloys ◽  
Three Dimensional ◽  
Atom Probe ◽  
Hard Magnetic Materials ◽  
Atom Clusters ◽  
Transmission Electron ◽  
Nucleation Sites ◽  
Final Microstructure ◽  
Crystallization Reaction ◽  
Primary Crystals

ABSTRACTThe nanocrystallization processes in Fe-Si-B-Nb-Cu and Fe-Nd-B(-Cu-Nb) amorphous alloys have been studied by transmission electron microscopy (TEM) and a three dimensional atom probe (3DAP). Cu additions are effective in refining the nanocrystalline microstructures of both alloys, because Cu atom clusters formed prior to the crystallization reaction serve as heterogeneous nucleation sites for the primary crystals. However, the clustering behaviors of Cu atoms in these two alloy systems are different, i.e., Cu completely dissolves in the Nd2Fe1 4B phase in the final microstructure of the Nd4.5Fe75.8B18.5Cu0.2Nb1 alloy, whereas CL' clusters grow to fcc-Cu particles in the Fe73.5Si13.5B9Nb3Cu1 alloy. The nanocrystallization processes in these two alloys clarified by the 3DAP results are compared.

APFIM Studies of Nanocrystallizations of Amorphous Alloys

1995 ◽  
Vol 400 ◽  
Author(s):  
K. Hono ◽  
Y. Zhang ◽  
A. Inoue ◽  
T. Sakurai
Keyword(s):  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
Primary Crystallization ◽  
Atom Probe ◽  
Nucleation And Growth ◽  
Cu Alloy ◽  
Nucleation Sites ◽  
Medium Range ◽  
Crystallization Reaction ◽  
Primary Crystals

AbstractThis paper reports recent atom probe analysis results of Fe-Zr-B(-Cu) and Al-Ni-Ce(-Cu) amorphous alloys, in which nanocrystalline microstructures develop by primary crystallization. In these alloy systems, enrichment of slow diffusing solute was found at the interfaces between primary crystals and amorphous matrix during the nucleation and growth stage. In the case of ternary Fe-Zr-B, no evidence for compositional heterogeneities were found prior to the onset of crystallization reaction. On the other hand, clustering of Cu atoms was observed in quaternary Fe-Zr-B-Cu alloy prior to the crystallization reaction. In the ternary Fe-Zr-B alloy, nucleation sites seem to be provided by the quenched-in nuclei which were observed as medium range ordered (MRO) domains by HREM. In the as-quenched Al-Ni-Ce(-Cu) alloy, compositional fluctuations were present from the as-quenched state. These observations suggest that nuclei for primary crystallization are provided in various forms such as MRO domains, solute clusters and compositional heterogeneities.

Effect of Additional Irradiation at Different Fluxes on RPV Embrittlement

2009 ◽  
Author(s):  
Kenji Dohi ◽  
Kenji Nishida ◽  
Akiyoshi Nomoto ◽  
Naoki Soneda ◽  
Hiroshi Matsuzawa ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Solute Atom ◽  
Volume Fraction ◽  
Neutron Fluence ◽  
Three Dimensional ◽  
Atom Probe ◽  
Atom Clusters ◽  
Neutron Fluences ◽  
The Difference ◽  
Test Reactor

The effect of the neutron flux at high fluence on the microstructural and hardness changes of a reactor pressure vessel (RPV) steel was investigated. An accelerated test reactor irradiation of a RPV material, previously irradiated in commercial reactors, was carried out at the lowest possible neutron fluxes in order to obtain neutron fluences up to approximately 1×1020 n/cm2 (E>1MeV). State-of-the-art experimental techniques such as three-dimensional atom probe were applied to carry out advanced quantitative characterization of defect features in the materials. Results for the same material irradiated in both high and low flux conditions are compared. For neutron fluences above 6×1019 n/cm2 (E>1MeV) the difference in the neutron fluence dependence of the increase in hardness is not seen for any neutron flux condition. The volume fraction of solute atom clusters increases linearly with neutron fluence, and the influence of neutron flux is not significant. The component elements and the chemical composition of the solute atom clusters formed by the irradiation do not change regardless of the neutron fluence and flux. The square root of the volume fraction of the solute atom clusters is a good correlation with the increase in hardness.

Atom Probe Microscopy and its Future

1994 ◽  
Vol 332 ◽  
Author(s):  
T. F. Kelly ◽  
P. P. Camus ◽  
D. J. Larson ◽  
L. M. Holzman
Keyword(s):  
Materials Science ◽  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Level ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Probe Field ◽  
Transmission Electron ◽  
Indispensable Tool ◽  
3D Information

ABSTRACTMuch of the current activity and excitement in materials science involves processing and understanding materials at the atomic scale. Accordingly, it is necessary for materials scientists to control and characterize materials at the atomic level. There are only a few microscopies that are capable of providing information about the structure of materials at the atomic level: the atom probe field ion microscope, the high resolution transmission electron microscope, and the scanning tunneling microscope. The three-dimensional atom probe (3DAP) determines the 3D location and elemental identity of each atom in a sample. It is the only technique that provides 3D information at the atomic scale.The origin and underlying concepts behind the 3DAP are described. Several examples of actual images from existing 3DAPs are shown with emphasis on nanometer-scale analysis. Current limitations of the technique and expected future developments in this form of microscopy are described. It is our opinion that 3D atomic-scale imaging will be an indispensable tool in materials science in the coming decades.

On the Role of Characterization in the Design of Interfaces in Nanoscale Materials Technology

2004 ◽  
Vol 10 (3) ◽  
pp. 324-335 ◽  
Author(s):  
S.P. Ringer ◽  
K.R. Ratinac
Keyword(s):  
Three Dimensional ◽  
Atom Probe ◽  
Turbine Rotor ◽  
Clay Nanocomposites ◽  
Multimodal Approach ◽  
Transmission Electron ◽  
Different Types ◽  
And Control

This work reviews recent research on the design and control of interfaces in engineering nanomaterials. Four case studies are presented that demonstrate the power of a multimodal approach to the characterization of different types of interfaces. We have used a combination of conventional, high resolution, and analytical transmission electron microscopy, microbeam electron diffraction, and three-dimensional atom probe to study polymer–clay nanocomposites, turbine rotor steels used for power generation, multicomponent aluminum alloys, and nanocrystalline magnetic materials.

scholarly journals Atom Scale Characterization of the Near Apex Region of an Atomic Force Microscope Tip

2010 ◽  
Vol 16 (5) ◽  
pp. 636-642 ◽  
Author(s):  
Christopher J. Tourek ◽  
Sriram Sundararajan
Keyword(s):  
Thin Film ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Atom Probe ◽  
Material Structure ◽  
Atomic Force ◽  
Transmission Electron ◽  
Afm Tips ◽  
Scale Characterization

AbstractThree-dimensional atom probe tomography (APT) is successfully used to analyze the near-apex regions of an atomic force microscope (AFM) tip. Atom scale material structure and chemistry from APT analysis for standard silicon AFM tips and silicon AFM tips coated with a thin film of Cu is presented. Comparison of the thin film data with that observed using transmission electron microscopy indicates that APT can be reliably used to investigate the material structure and chemistry of the apex of an AFM tip at near atomic scales.

scholarly journals Detection and Determination of Solute Carbon in Grain Interior to Correlate with the Overall Carbon Content and Grain Size in Ultra-Low-Carbon Steel

2013 ◽  
Vol 19 (S5) ◽  
pp. 66-68 ◽  
Author(s):  
Jiling Dong ◽  
Yinsheng He ◽  
Chan-Gyu Lee ◽  
Byungho Lee ◽  
Jeongbong Yoon ◽  
...  
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Carbon Content ◽  
Three Dimensional ◽  
Low Carbon Steel ◽  
Atom Probe ◽  
Optical Microscope ◽  
Low Carbon ◽  
Transmission Electron ◽  
Solute Carbon

AbstractIn this study, every effort was exerted to determine and accumulate data to correlate microstructural and compositional elements in ultra-low-carbon (ULC) steels to variation of carbon content (12–44 ppm), manganese (0.18–0.36%), and sulfur (0.0066–0.001%). Quantitative analysis of the ULC steel using optical microscope, scanning electron microscope, transmission electron microscope, and three-dimensional atom probe revealed the decrease of grain size and dislocation density with the increase of carbon contents and/or increase of the final delivery temperature. For a given carbon content, the grain interior carbon concentration increases as the grain size increases.

Quantitative Correlation between Strength, Ductility and Precipitate Microstructures with PFZ in Al-Zn-Mg(-Ag, Cu) Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 431-436 ◽  
Author(s):  
Tomo Ogura ◽  
Shoichi Hirosawa ◽  
Alfred Cerezo ◽  
Tatsuo Sato
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Three Dimensional ◽  
Atom Probe ◽  
The Other ◽  
Proof Stress ◽  
Quantitative Correlation ◽  
Cu Alloys ◽  
Transmission Electron ◽  
Initial Stage

The quantitative correlation between strength, ductility and precipitate microstructures in the vicinity of grain boundaries with precipitate free zones (PFZ) was evaluated for Al-Zn-Mg(-Ag, Cu) alloys using transmission electron microscopy (TEM), three-dimensional atom probe (3DAP) and tensile test. In the Al-Zn-Mg ternary and Cu-added alloys aged at 433K, larger widths of PFZ were observed by TEM and resulted in lower elongations to fracture, independent of the size of grain boundary precipitates. On the other hand, the elongation of the Ag-added alloy was higher, if compared at the same levels of proof stress, due to the much smaller width of PFZ. This strongly suggests that PFZ is harmful to fracture of the investigated alloys. From a 3DAP analysis, furthermore, it was revealed that Ag and Cu atoms are incorporated in the nanoclusters from the initial stage of aging. In this work, the elongation was well correlated to the width of PFZ, size of grain boundary precipitates and the level of proof stress, enabling to predict ductility of the alloys from known microstructural factors.

Apfim and HREM Studies of Nanocomposite Soft and Hard Magnetic Materials

1998 ◽  
Vol 4 (S2) ◽  
pp. 108-109
Author(s):  
K. Hono ◽  
D. H. Ping ◽  
M. Ohnuma
Keyword(s):  
High Resolution Electron Microscopy ◽  
Atom Probe ◽  
Hard Magnetic Materials ◽  
Probe Field ◽  
Field Ion Microscopy ◽  
Cu Alloy ◽  
Nucleation Sites ◽  
Resolution Electron ◽  
Ferromagnetic Exchange ◽  
Ion Microscopy

Atom probe field ion microscopy is the most suitable technique for determining local chemical composition changes during nanocrystallization processes of amorphous alloys. In this talk, we report atom probe field ion microscopy (APFIM) and high resolution electron microscopy (HREM) studies on nanocrystallization processes in Fe-Si-B-Nb-Cu soft magnet and Fe-Nd-B-Co-Ga exchange spring magnet.Fe or Co based alloys with nanocrystalline microstructure show excellent permeability because the net magnetocrystalline anisotropy is significantly reduced when the grain size becomes smaller than the ferromagnetic exchange length. Fe-Si-B-Nb-Cu alloy is the pioneering nanocrystalline soft magnetic material invented by Yoshizawa et al. in 1988 [1]. Our previous works [2,3] reported evidence for clustering of Cu prior to the onset of the crystallization reaction. However, in the previous studies, it was not confirmed that these Cu clusters work as heterogeneous nucleation sites for a-Fe primary crystals.

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