Activation Distance Determination of Rate Controlling Obstacles in the Age Hardening of a Quasi-Binary Al-Mg2Si Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 455-460
Author(s):  
Bradley Diak ◽  
Rathna Lanerolle
Keyword(s):  
Three Dimensional ◽  
Natural Aging ◽  
Rate Sensitivity ◽  
Atom Probe ◽  
Single Step ◽  
Age Hardening ◽  
Distance Analysis ◽  
Acta Mater ◽  
Ice Water

The age hardening response of a quasi-binary Al-Mg2Si alloy was studied using activation distance analysis of precise strain rate sensitivity experiments at 78 and 300K. The alloy of Al-0.7Mg-0.33Si-0.024Fe-0.006Ti(at.%) has a stochiometrically balanced composition of Mg2Si. The alloy was solutionized at 550°C and ice water quenched before ageing in one of two ways: single-step or multi-step ageing. For single-step ageing: specimens were naturally aged for 70 days at room temperature (RT); pre-aged for 16 hours at 70°C; or artificially aged for 30 min or 10 hours at 175°C. For multi-step ageing: specimens were pre-aged at 70°C for 16 hours after natural ageing for 70 days at RT; artificially aged for 30 min or 10 hours at 175°C after pre-aging at 70°C for 16 hours; or artificially aged for 10 hours at 175°C after natural aging for 70 days at RT. The activation analysis reveals rate controlling obstacle dimensions ranging from 0.3 to 10 nm depending upon the ageing condition. A comparison is made to a prior three dimensional atom probe ageing study of the same alloy [Murayama and Hono, Acta Mater., 47 (1999) 1537-1578.].

Nano-Scale Clusters Formed in the Early Stage of Phase Decomposition of Al-Mg-Si Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 357-360 ◽  
Author(s):  
Shoichi Hirosawa ◽  
Tatsuo Sato
Keyword(s):  
Early Stage ◽  
Sheet Material ◽  
Three Dimensional ◽  
Natural Aging ◽  
Aging Treatment ◽  
Atom Probe ◽  
Phase Decomposition ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Nano Scale

The formation of nano-scale clusters (nanoclusters) prior to the precipitation of the strengthening b” phase significantly influences two-step aging behavior of Al-Mg-Si alloys. In this work, the existence of two kinds of nanoclusters has been verified in the early stage of phase decomposition by differential scanning calorimetry (DSC) and three-dimensional atom probe (3DAP). Pre-aging treatment at 373K before natural aging was also found to form preferentially one of the two nanoclusters, resulting in the remarkable restoration of age-hardenability at paint-bake temperatures. Such microstructural control by means of optimized heat-treatments; i.e. nanocluster assist processing (NCAP), possesses great potential for enabling Al-Mg-Si alloys to be used more widely as a body-sheet material of automobiles.

scholarly journals Analysis of Three-dimensional Atom-probe Data by the Proximity Histogram

2000 ◽  
Vol 6 (05) ◽  
pp. 437-444 ◽  
Author(s):  
Olof C. Hellman ◽  
Justin A. Vandenbroucke ◽  
Järg Rüsing ◽  
Dieter Isheim ◽  
David N. Seidman
Keyword(s):  
Quantitative Determination ◽  
Three Dimensional ◽  
Atom Probe ◽  
Radius Of Curvature ◽  
Data Compilation ◽  
Composition Profiles ◽  
Interfacial Segregation ◽  
Crystallographic Defects ◽  
20 Nm

Abstract The three-dimensional (3D) atom-probe technique produces a reconstruction of the elemental chemical identities and three-dimensional positions of atoms field evaporated from a sharply pointed metal specimen, with a local radius of curvature of less than 50 nm. The number of atoms collected can be on the order of one million, representing an analysis volume of approximately 20 nm × 20 nm × 200 nm (80,000 nm3). This large amount of data allows for the identification of microstructural features in a sample, such as grain or heterophase boundaries, if the feature density is large enough. Correlation of the measured atomic positions with these identified features results in an atom-by-atom description of the chemical environment of crystallographic defects. This article outlines a data compilation technique for the generation of composition profiles in the vicinity of interfaces in a geometrically independent way. This approach is applied to quantitative determination of interfacial segregation of silver at a MgO/Cu(Ag) heterophase interface.

Identification of 2D Boundaries from 3D Atom Probe Data, and Spatial Correlation of Atomic Distributions with Interfaces

1999 ◽  
Vol 578 ◽  
Author(s):  
O.C. Hellman ◽  
J.A. Vandenbroucke ◽  
J. Rüsing ◽  
D. Isheim ◽  
D.N. Seidman
Keyword(s):  
Quantitative Determination ◽  
Spatial Correlation ◽  
Three Dimensional ◽  
Atom Probe ◽  
Real Space ◽  
Interfacial Segregation ◽  
Crystallographic Defects ◽  
20 Nm ◽  
Interface Geometry

AbstractThe Three Dimensional Atom Probe produces a real space map of the elemental identities and positions of atoms field-evaporated from a sharply pointed specimen. The analyzed volume is on the order of 20 nm × 20 nm × 100 nm. This is large enough to enclose microstructural features such as grain- or heterophase boundaries. Correlation of the measured atomic positions with such features results in an atom-by-atom description of the chemical environment of these crystallographic defects. We describe here a method for identifying these interfaces and profiling the composition in the vicinity of the interfaces without any assumptions about the interface geometry. This approach is applied to quantitative determination of interfacial segregation of Ag at a MgO/Cu(Ag) heterophase interface. We discuss the implications of our technique with respect to classical treatments of segregation at interfaces.

A New Approach to the Determination of Concentration Profiles in Atom Probe Tomography

2012 ◽  
Vol 18 (2) ◽  
pp. 359-364 ◽  
Author(s):  
Peter J. Felfer ◽  
Baptiste Gault ◽  
Gang Sha ◽  
Leigh Stephenson ◽  
Simon P. Ringer ◽  
...  
Keyword(s):  
Atom Probe Tomography ◽  
Three Dimensional ◽  
Atom Probe ◽  
Solute Concentration ◽  
Concentration Profiles ◽  
Field Evaporation ◽  
New Approach ◽  
Depth Direction ◽  
Spread Function

AbstractAtom probe tomography (APT) provides three-dimensional analytical imaging of materials with near-atomic resolution using pulsed field evaporation. The processes of field evaporation can cause atoms to be placed at positions in the APT reconstruction that can deviate slightly from their original site in the material. Here, we describe and model one such process—that of preferential retention of solute atoms in multicomponent systems. Based on relative field evaporation probabilities, we calculate the point spread function for the solute atom distribution in the “z,” or in-depth direction, and use this to extract more accurate solute concentration profiles.

scholarly journals Estimation of the Reconstruction Parameters for Atom Probe Tomography

2008 ◽  
Vol 14 (4) ◽  
pp. 296-305 ◽  
Author(s):  
Baptiste Gault ◽  
Frederic de Geuser ◽  
Leigh T. Stephenson ◽  
Michael P. Moody ◽  
Barrington C. Muddle ◽  
...  
Keyword(s):  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
Atom Probe ◽  
Field Of View ◽  
Wide Field ◽  
Detection Systems ◽  
Wide Field Of View ◽  
Systematic Determination ◽  
Consistent Method

The application of wide field-of-view detection systems to atom probe experiments emphasizes the importance of careful parameter selection in the tomographic reconstruction of the analyzed volume, as the sensitivity to errors rises steeply with increases in analysis dimensions. In this article, a self-consistent method is presented for the systematic determination of the main reconstruction parameters. In the proposed approach, the compression factor and the field factor are determined using geometrical projections from the desorption images. A three-dimensional Fourier transform is then applied to a series of reconstructions, and after comparing to the known material crystallography, the efficiency of the detector is estimated. The final results demonstrate a significant improvement in the accuracy of the reconstructed volumes.

Interaction between Cu and Sn in the Early Stages of Ageing of Al-1.7at.%Cu-0.01at.%Sn

2006 ◽  
Vol 519-521 ◽  
pp. 495-500 ◽  
Author(s):  
Laure Bourgeois ◽  
Timothy Wong ◽  
X.Y. Xiong ◽  
Jian Feng Nie ◽  
Barry C. Muddle
Keyword(s):  
Three Dimensional ◽  
Atom Probe ◽  
Age Hardening ◽  
Peak Hardness ◽  
Artificial Ageing ◽  
Natural Ageing ◽  
Number Density ◽  
Transmission Electron ◽  
Hardening Treatment ◽  
Significant Acceleration

The interaction between vacancies and Sn and Cu solute atoms in an Al-1.7at.%Cu- 0.01at.%Sn alloy was investigated by exploring the effect of incorporating natural ageing into conventional age hardening treatment. It was found that provided the artificial ageing temperature does not exceed a critical value between 160°C and 200°C, a narrow window of natural ageing (3-100 h) will result in a significant acceleration of the age hardening response and no decrease in peak hardness. Transmission electron microscopy showed that this effect reflects a large and rapid increase in number density of Cu GP(I) zones, and, to a lesser extent, of θ". The distribution and number density of θ' are essentially unaffected. Three-dimensional atom probe provided strong evidence that refinement of GP(I) zone distribution is not due to clustering of Cu atoms onto pre-existing Sn clusters. Instead it appears to be caused by a subtle interaction between vacancies, Sn and Cu atoms.

Effects of Sn Addition on Clustering and Age-Hardening Behavior in a Pre-Aged Al-Mg-Si Alloy

2016 ◽  
Vol 877 ◽  
pp. 455-460 ◽  
Author(s):  
Hisao Shishido ◽  
Yasuo Takaki ◽  
Masaya Kozuka ◽  
Katsushi Matsumoto ◽  
Yasuhiro Aruga
Keyword(s):  
Cluster Formation ◽  
Natural Aging ◽  
Atom Probe ◽  
The Other ◽  
Endothermic Peak ◽  
Age Hardening ◽  
Number Density ◽  
Scanning Calorimetry ◽  
Hardening Behavior ◽  
Other Hand

The effects of Sn addition on clustering and age-hardening behavior in an Al-0.6Mg-1.0Si (mass %) alloy were investigated. Addition of Sn delayed the age-hardening in single aging at 170 ̊C. On the other hand, Sn promoted the age-hardening response in 3-step aging process which comprises a pre-aging (PA) at 90 ̊C for 18ks followed by natural aging (NA) for 604.8ks and artificial aging (AA) at 170 ̊C. The characteristics of clusters formed during PA and NA were evaluated by differential scanning calorimetry (DSC) analysis and atom probe tomography (APT). The DSC results show that the endothermic peak at around 160 ̊C to 200 ̊C was observed in the Sn-free alloy. On the other hand, in the Sn-added alloy, endothermic peak was not observed. It is suggested that Sn addition suppresses the formation of the clusters formed during NA. The APT results show that the Sn addition decreases the number density of clusters, especially smaller clusters. No Sn precipitates were found in Mg-Si precipitates formed during AA at 170 ̊C for 3.6ks. It is speculated that suppression of smaller cluster formation by addition of Sn promotes the age-hardening response

Electrochemical sensor based on hierarchical nickel oxide nanostructure doped with indium ions for voltammetric simultaneous determination of sunset yellow and tartrazine colorants in soft drink powders

2021 ◽  
Author(s):  
Mohammad Mehdi Moarefdoust ◽  
Shohreh Jahani ◽  
Mehran Moradalizadeh ◽  
Mohammad Mehdi Motaghi ◽  
Mohammad Mehdi Foroughi
Keyword(s):  
Nickel Oxide ◽  
Electrochemical Sensor ◽  
Simultaneous Determination ◽  
Soft Drink ◽  
Three Dimensional ◽  
Single Step ◽  
Simple Approach ◽  
Sunset Yellow ◽  
Hierarchical Nanostructure

The current study was designed to develop a single-step and simple approach to effectively fabricate three-dimensional raspberry-like In3+/NiO hierarchical nanostructure (In3+/NiO RLHNSs) as a modifier, which was subsequently characterized by...

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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