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.

A Combined TEM and Atom Probe Approach to Analyse the Early Stages of Age Hardening in AA 6016

2016 ◽  
Vol 877 ◽  
pp. 231-236 ◽  
Author(s):  
Olaf Engler ◽  
C. Schäfer ◽  
Henk Jan Brinkman ◽  
Calin D. Marioara ◽  
Masaya Kozuka ◽  
...  
Keyword(s):  
Atom Probe ◽  
Age Hardening ◽  
Artificial Ageing ◽  
Phase Decomposition ◽  
Number Density ◽  
Early Stages ◽  
Transmission Electron ◽  
Different Types ◽  
6Xxx Series ◽  
Insight Into

In this study we aim at combining the results from transmission electron microscopy (TEM) and atom probe tomography (APT) to study the early stages of phase decomposition in the age hardening alloy AA 6016. Samples are subjected to different periods of natural ageing or artificial pre-ageing at elevated temperature in order to produce different types of clusters and early stages of precipitation before age hardening commences. APT is utilized to detect clusters and identify their compositions, whereas TEM is applied to analyse and quantify number density and sizes of the particles during artificial ageing at 185°C. It is shown that the two techniques, TEM and APT, are complementary and a combined approach yields more detailed insight into the early stages of phase decomposition in age hardening 6xxx series alloys than possible by the sole use of either technique individually.

Evolution of Nanostructure during the Early Stages of Ageing in Al-Zn-Mg-Cu Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 555-560 ◽  
Author(s):  
Peter V. Liddicoat ◽  
Tomoyuki Honma ◽  
L.T. Stephenson ◽  
Simon P. Ringer
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Age Hardening ◽  
Peak Hardness ◽  
Cu Alloys ◽  
Transmission Electron ◽  
Element Species ◽  
Hardness Increase ◽  
Solute Interactions ◽  
Effect Of Copper

During age-hardening of certain Al-Zn-Mg-Cu alloys, a 90% hardness increase can occur with 75 seconds. The clustering and precipitation of solute element species during this early rapid hardening (RH) period has been investigated through atom probe tomography, transmission electron microscopy, and Vickers hardness measurements. This study has focussed on the effect of copper by analysing three alloys; Al-2.0Zn-1.8Mg-0.7Cu, Al-2.0Zn-1.7Mg-0.2Cu and Al-1.9Zn-1.7Mg (at.%). The early RH reaction in these alloys accounts for up to 70% of the total hardening (peak hardness minus as-quenched hardness) and takes place during the first 60 seconds of ageing. We report preferred solute-solute interactions in the as-quenched materials. This quenched-in nanostructure acts as a template for subsequent solute clustering, the nature of which we have correlated with ageing.

Influence of Pre-Straining and Pre-Ageing on the Age-Hardening Response of Al-Mg-Si Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 903-908 ◽  
Author(s):  
Yong Yan ◽  
Ze Qin Liang ◽  
John Banhart
Keyword(s):  
Differential Scanning Calorimetry ◽  
Cluster Formation ◽  
Age Hardening ◽  
Peak Hardness ◽  
Artificial Ageing ◽  
Natural Ageing ◽  
Scanning Calorimetry ◽  
Negative Effect ◽  
Kinetics Of ◽  
Positive Effect

The effect of pre-straining and pre-ageing on the age hardening response of Al-0.6%Mg-0.8%Si alloy is studied by Vickers hardness and differential scanning calorimetry (DSC). It is found that pre-ageing can suppress the formation of unwanted clusters and keeps the structure stable for a certain time. A pre-ageing treatment can effectively reduce or avoid the negative effect of natural ageing on artificial ageing and even produce a positive effect. Cluster formation can also be reduced by pre-straining, but the kinetics of clustering is still similar to that of the as-quenched condition. In contrast, after pre-straining, the peak positions of β and β move to lower temperatures and peak hardness is achieved in a shorter time, indicating that the formation of β and β is accelerated by pre-straining. However, the negative effect of natural ageing still persists after pre-straining. Pre-straining before pre-aging can take advantage of both techniques and produce a positive strength response. For pre-straining after pre-aging, pre-straining tends to destabilize the structure created by pre-ageing and can reactivate the clustering process, which has negative effect on subsequent artificial ageing.

The Influence of Tungsten on the Chemical Composition of a Temporally Evolving Nanostructure of a Model Ni-Al-Cr Superalloy

2004 ◽  
Vol 10 (3) ◽  
pp. 355-365 ◽  
Author(s):  
Chantal K. Sudbrack ◽  
Dieter Isheim ◽  
Ronald D. Noebe ◽  
Nathan S. Jacobson ◽  
David N. Seidman
Keyword(s):  
Temporal Evolution ◽  
Three Dimensional ◽  
Quaternary Alloy ◽  
Atom Probe ◽  
Concentration Profiles ◽  
Number Density ◽  
Concentration Gradients ◽  
Two Phase ◽  
Spatially Resolved ◽  
Transmission Electron

The influence of W on the temporal evolution of γ′ precipitation toward equilibrium in a model Ni-Al-Cr alloy is investigated by three-dimensional atom-probe (3DAP) microscopy and transmission electron microscopy (TEM). We report on the alloys Ni-10 Al-8.5 Cr (at.%) and Ni-10 Al-8.5 Cr-2 W (at.%), which were aged isothermally in the γ + γ′ two-phase field at 1073 K, for times ranging from 0.25 to 264 h. Spheroidal-shaped γ′ precipitates, 5–15 nm diameter, form during quenching from above the solvus temperature in both alloys at a high number density (∼1023m−3). As γ′ precipitates grow with aging at 1073 K, a transition from spheriodal- to cuboidal-shaped precipitates is observed in both alloys. The elemental partitioning and spatially resolved concentration profiles across the γ′ precipitates are obtained as a function of aging time from three-dimensional atom-by-atom reconstructions. Proximity histogram concentration profiles (Hellman et al., 2000) of the quaternary alloy demonstrate that W concentration gradients exist in γ′ precipitates in the as-quenched and 0.25-h aging states, which disappear after 1 h of aging. The diffusion coefficient of W in γ′ is estimated to be 6.2 × 10−20m2s−1at 1073 K. The W addition decreases the coarsening rate constant, and leads to stronger partitioning of Al to γ′ and Cr to γ.

scholarly journals Transmission electron microscopy analysis of the crystallography of precipitates in Mg–Sn alloys aged at high temperatures

2014 ◽  
Vol 47 (5) ◽  
pp. 1729-1735 ◽  
Author(s):  
Xin Nie ◽  
Yimin Guan ◽  
Dongshan Zhao ◽  
Yu Liu ◽  
Jianian Gui ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Three Dimensional ◽  
Dark Field ◽  
Peak Hardness ◽  
Invariant Line ◽  
Orientation Relationships ◽  
Transmission Electron Microscopy Analysis ◽  
Transmission Electron ◽  
Annular Dark Field

The crystallographic orientation relationships (ORs) of precipitated β-Mg2Sn particles in Mg–9.76 wt% Sn alloy aged at 573 K for 5 h, corresponding to its peak hardness, were investigated by advanced transmission electron microscopy (TEM). OR-3 of (110)β//(0001)αand [\overline 111]β//[1\overline 210]αand OR-4 of (110)β//(0001)αand [001]β//[2\overline 1\overline 10]αare the key ORs of β-Mg2Sn particles in the alloy. The proportions of β-Mg2Sn particles exhibiting OR-3 and OR-4 were determined as 75.1 and 24.3%, respectively. Crystallographic factors determined the predominance of OR-3 in the precipitated β-Mg2Sn particles. This mechanism was analyzed by a three-dimensional invariant line model constructed using a transformation matrix in reciprocal space. Models of the interface of precipitated β-Mg2Sn and the α-Mg matrix were constructedviahigh-resolution TEM and atomic resolution high-angle annular dark-field scanning TEM.

Effect of Cu on Nanoscale Precipitation Evolution and Mechanical Properties of a Fe–NiAl Alloy

2017 ◽  
Vol 23 (2) ◽  
pp. 350-359 ◽  
Author(s):  
Qin Shen ◽  
Hao Chen ◽  
Wenqing Liu
Keyword(s):  
Mechanical Properties ◽  
Atom Probe Tomography ◽  
Diffusion Rate ◽  
Atom Probe ◽  
Peak Hardness ◽  
Dramatic Improvement ◽  
Number Density ◽  
Cu Alloy ◽  
Tension Tests ◽  
Nial Alloy

AbstractThe microstructural evolution of precipitation in two model alloys, Fe–NiAl and Fe–NiAl–Cu, was investigated during aging at 500°C for different times using atom probe tomography (APT). The APT results reveal that the addition of Cu effectively increases the number density of NiAl precipitates. This is attributed to Cu promoting the nucleation of NiAl particles by increasing the chemical driving force and decreasing the interfacial energy. The NiAl precipitates of the Fe–NiAl–Cu alloy grow and coarsen at a slower rate than that of the Fe–NiAl alloy, mainly due to the slower diffusion rate of the Cu atoms. The mechanical properties of the two alloys were characterized by Vickers hardness and tension tests. It was found that the addition of Cu results in the formation of core–shell precipitates with a Cu-rich core and a NiAl shell, leading to a dramatic improvement of peak hardness and strength. The effect of Cu on precipitation strengthening is discussed in terms of chemical strength and coherency strength.

The Effect of Pre-Ageing and Addition of Copper on the Precipitation Behaviour in Al-Mg-Si Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 543-548 ◽  
Author(s):  
A.I. Morley ◽  
M.W. Zandbergen ◽  
Alfred Cerezo ◽  
George D.W. Smith
Keyword(s):  
Aluminium Alloys ◽  
Deleterious Effect ◽  
Atom Probe ◽  
Artificial Ageing ◽  
Strengthening Effect ◽  
Natural Ageing ◽  
Aged Material ◽  
3 Dimensional ◽  
Precipitation Behaviour ◽  
6Xxx Series

Hardness measurements and 3-dimensional atom probe analysis have been used to characterise the precipitation behaviour in two 6xxx series aluminium alloys, one Cu-free alloy (Al-0.78at%Mg- 0.68at%Si) and one Cu-containing alloy (Al-0.78at%Mg-0.68at%Si-0.30at%Cu). The heat treatments consisted of either natural ageing or pre-ageing at 353K followed by a paint-bake treatment at 453K. Natural ageing was seen to increase the hardness, and hence reduce formability compared to pre-ageing. In addition, the strengthening effect of artificial ageing was less after natural ageing than after pre-ageing. In the Cu-free alloy, needle-like β″ was observed to form only after a pre-ageing treatment during the first 60 minutes of a paint-bake treatment. In the Cucontaining alloy, needle-like β″ formed during paint bake in both the naturally-aged and pre-aged material, although it is formed more rapidly after pre-ageing. This was accompanied by an increase in strength over the Cu-free alloy and indicates that Cu reduces the deleterious effect of natural ageing.

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.

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.

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