The Effect of Elastic Straining on a 6060 Aluminium Alloy during Natural or Artificial Ageing

2014 ◽  
Vol 794-796 ◽  
pp. 1205-1210
Author(s):  
Eva A. Mørtsell ◽  
Ida Westermann ◽  
Calin D. Marioara ◽  
Ketill O. Pedersen ◽  
Sigmund J. Andersen ◽  
...  
Keyword(s):  
Reference Material ◽  
Elastic Strain ◽  
Artificial Ageing ◽  
Natural Ageing ◽  
Transmission Electron ◽  
Significant Difference ◽  
Precipitate Microstructure ◽  
Increased Strength ◽  
Reference Samples ◽  
Strained Material

The effect on hardness and precipitate microstructure of elastically straining a 6060 Al-Mg-Si alloy during natural ageing or artificial ageing has been investigated. The elastic strain is here defined as 50 % of the material yield strength. All heat treatments where elastic straining was applied led to an increased hardness compared to the unstrained reference material. Quantitative investigations of the precipitate microstructure using transmission electron microscopy (TEM) did not indicate any significant difference in precipitate parameters as compared to the unstrained reference material. Therefore the increased strength in the elastically strained material is being linked to strain induced dislocations based on faster ageing kinetics compared to unstrained reference samples.

scholarly journals Combined effect of Sn addition and pre-ageing on natural secondary and artificial ageing of Al–Mg–Si alloys

2022 ◽  
Author(s):  
Xingpu Zhang ◽  
Meng Liu ◽  
Jiangwei Wang ◽  
Jixue Li ◽  
John Banhart
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Electrical Resistivity ◽  
Combined Effect ◽  
Artificial Ageing ◽  
Combined Effects ◽  
Natural Ageing ◽  
Scanning Calorimetry ◽  
Transmission Electron

AbstractBoth Sn addition and pre-ageing are known to be effective in maintaining the artificial ageing potential after natural ageing of Al–Mg–Si alloys. In this study, the combined effects of Sn addition and pre-ageing at 100 °C or 180 °C on natural secondary ageing and subsequent artificial ageing of an alloy AA6014 were investigated using hardness, electrical resistivity, differential scanning calorimetry and transmission electron microscopy characterizations. It is found that pre-ageing can suppress natural secondary ageing and improve the artificial ageing hardening kinetics and response after 1 week of natural secondary ageing in both alloys with and without Sn addition. The effect of pre-ageing at 100 °C is more pronounced in the Sn-free alloy while the combination of pre-ageing at 180 °C and adding Sn shows superiority in suppressing natural secondary ageing and thus avoiding the undesired hardening before artificial ageing. Moreover, when natural ageing steps up to 8 h are applied before pre-ageing at 100 °C, the effect of pre-ageing in Sn-added alloy can be further improved. The influence of Sn on vacancies at different ageing temperatures is discussed to explain the observed phenomena. Graphical abstract

scholarly journals Natural and artificial ageing of spruce wood as observed by FTIR-ATR and UVRR spectroscopy

Holzforschung ◽  
2012 ◽  
Vol 66 (2) ◽  
Author(s):  
Christelle Ganne-Chédeville ◽  
Anna-Stiina Jääskeläinen ◽  
Julien Froidevaux ◽  
Mark Hughes ◽  
Parviz Navi
Keyword(s):  
Principal Component ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Artificial Ageing ◽  
Wood Structure ◽  
Natural Ageing ◽  
Significant Extent ◽  
Spruce Wood ◽  
Ultraviolet Resonance Raman ◽  
Reference Samples

Abstract Spruce samples, naturally aged for 200, 400 and 500 years, artificially aged by a hydrothermal treatment (at 180, 160 or 130°C, relative air humidities of 14%, 40%, or 60% and for treatment times between 1 to 50 h), as well as reference samples, were analysed by Fourier transform infrared spectroscopy (FTIR) attenuated total reflection (FTIR-ATR) and ultraviolet resonance Raman (UVRR) spectroscopy. Natural ageing mostly affected the hemicelluloses and lignin, as observed from the FTIR-ATR and UVRR spectra, respectively. The UVRR spectra of the same samples after acetone extraction indicated that lignin was partially degraded and quinone structures were possibly formed. Artificial ageing at 160°C showed a significant change in the lignin structure, a well-known effect in the thermal treatment of wood, whereas treatment at 130°C did not alter the wood structure to any significant extent. Principal component analysis of the UVRR spectra confirmed that the spectra of artificially aged wood up to 160°C are dissimilar to naturally aged wood and which are also dissimilar to unaged wood.

Precipitation Sequences in Two Al-Li-Cu Alloys

2011 ◽  
Vol 172-174 ◽  
pp. 267-272 ◽  
Author(s):  
Benjamin Decreus ◽  
Frédéric de Geuser ◽  
Alexis Deschamps ◽  
Patricia Donnadieu ◽  
Christophe Sigli
Keyword(s):  
Room Temperature ◽  
Alloy Composition ◽  
Nucleation And Growth ◽  
Artificial Ageing ◽  
Natural Ageing ◽  
X Ray ◽  
X Ray Scattering ◽  
Cu Alloys ◽  
Transmission Electron ◽  
Synchrotron Light

The precipitation sequences in two Al-Li-Cu alloys with similar Cu concentration and different Li concentration have been studied by small-angle X-ray scattering using synchrotron light, in combination with transmission electron microscopy. The sequence ranges from phases formed during natural ageing to the hardening ones obtained by artificial ageing at 155°C. It is found that the low Li-containing alloy shows first Cu-rich clusters at room temperature followed by T1 precipitates, while the high Li-containing alloy shows first δ’-Al3Li precipitates and then formation of T1 phase in coexistence with the δ’. The influence of alloy composition on T1 nucleation and growth kinetics is discussed in light of the experimental results.

scholarly journals Influence of quench rate on multi-stage ageing of AA6014 alloy

2020 ◽  
Vol 326 ◽  
pp. 02005
Author(s):  
Zi Yang ◽  
Xiaohe Jiang ◽  
Xingpu Zhang ◽  
Meng Liu ◽  
Zeqin Liang ◽  
...  
Keyword(s):  
Cluster Formation ◽  
Artificial Ageing ◽  
Natural Ageing ◽  
Quench Rate ◽  
Positron Annihilation Lifetime ◽  
Multi Stage ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Means Of Transmission ◽  
Fast Quenching

The influence of quench rate after solution heat treatment on the microstructure in the as-quenched state and subsequent ageing kinetics of alloy AA6014 was investigated by means of transmission electron microscopy, positron annihilation lifetime spectroscopy and hardness measurements. Various ageing temperatures and stages were taken into consideration. Consistent with previous studies, we found that solute and vacancy supersaturation decrease during slow quenching due to precipitation and annihilation, respectively. Additionally, we observed cluster formation during cooling below 200 °C. As for the influence on ageing behaviour we observe different behaviour for high and low ageing temperature: Artificial ageing is more affected than pre-ageing and natural secondary ageing. The detrimental effect of natural ageing on paint-bake hardening also depends on the quench rate. Possible interpretations are associated with cluster formation during natural ageing and also during quenching. The influence of pre-ageing at different temperatures on subsequent ageing kinetics is similar for slower industrial-type quenching and for fast quenching, thus allowing to apply the findings from idealised quenching conditions to situations closer to real application.

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.

Strain analysis with nanometer resolution using a conventional transmission electron microsopy technique: electron diffraction contrast imaging revisited

1995 ◽  
Vol 53 ◽  
pp. 168-169
Author(s):  
Koenraad G F Janssens ◽  
Omer Van der Biest ◽  
Jan Vanhellemont ◽  
Herman E Maes ◽  
Robert Hull
Keyword(s):  
Electron Diffraction ◽  
Strain Field ◽  
Elastic Strain ◽  
Strain Analysis ◽  
Local Strain ◽  
Contrast Imaging ◽  
Strain Characterization ◽  
Physical Mechanisms ◽  
Diffraction Contrast ◽  
Transmission Electron

There is a growing need for elastic strain characterization techniques with submicrometer resolution in several engineering technologies. In advanced material science and engineering the quantitative knowledge of elastic strain, e.g. at small particles or fibers in reinforced composite materials, can lead to a better understanding of the underlying physical mechanisms and thus to an optimization of material production processes. In advanced semiconductor processing and technology, the current size of micro-electronic devices requires an increasing effort in the analysis and characterization of localized strain. More than 30 years have passed since electron diffraction contrast imaging (EDCI) was used for the first time to analyse the local strain field in and around small coherent precipitates1. In later stages the same technique was used to identify straight dislocations by simulating the EDCI contrast resulting from the strain field of a dislocation and comparing it with experimental observations. Since then the technique was developed further by a small number of researchers, most of whom programmed their own dedicated algorithms to solve the problem of EDCI image simulation for the particular problem they were studying at the time.

Effect of Concentration of Trisodium Citrate Anticoagulant on Calculation of the International Normalised Ratio and the International Sensitivity Index of Thromboplastin

1994 ◽  
Vol 72 (01) ◽  
pp. 084-088 ◽  
Author(s):  
E M Duncan ◽  
C R Casey ◽  
B M Duncan ◽  
J V Lloyd
Keyword(s):  
Reference Material ◽  
Oral Anticoagulants ◽  
Reference Method ◽  
Trisodium Citrate ◽  
Sensitivity Index ◽  
Blood Samples ◽  
Orthogonal Regression ◽  
Significant Difference ◽  
International Normalised Ratio ◽  
International Sensitivity Index

SummaryThe aim of this study was to determine whether the concentration of trisodium citrate used to anticoagulate blood has an effect on the INR of the sample and the ISI of the thromboplastin. Five thromboplastins including and Australian reference material were used to measure the prothrombin time of normal and patient samples collected into two concentrations of trisodium citrate - 109 mM and 129 mM. There was no effect of citrate concentration on the INRs determined with the reference material. However for the other four thromboplastins there was a significant difference between INRs for the two citrate groups. The prothrombin times of the samples collected into 129 mM were longer than those collected into 109 mM. This difference was only slight in normal plasma but more marked in patients receiving oral anticoagulants, causing the INRs for patient plasmas collected into 129 mM citrate to be higher then the corresponding samples collected into 109 mM citrate.From orthogonal regression of log prothrombin times by the reference method against each thromboplastin, we found that the ISI for each thromboplastin was approximately 10% lower when determined with samples collected into 129 mM citrate than with samples collected into 109 mM. These results suggest that the concentration of trisodium citrate used for collection of blood samples can affect the calculation of the INR and the calibration of the ISI of thromboplastin. This was found both for commercial thromboplastins prepared by tissue extraction and for a recombinant tissue factor.

Effect of natural ageing and pre-straining on the hardening behaviour and microstructural response during artificial ageing of an Al–Mg–Si–Cu alloy

2016 ◽  
Vol 95 ◽  
pp. 329-339 ◽  
Author(s):  
Deyan Yin ◽  
Qiao Xiao ◽  
Yuqiang Chen ◽  
Huiqun Liu ◽  
Danqing Yi ◽  
...  
Keyword(s):  
Artificial Ageing ◽  
Natural Ageing ◽  
Cu Alloy

Oxide scale behavior of Al–7.5 mass%Mg alloy containing trace Ca during short-term oxidation

2021 ◽  
Vol 11 (11) ◽  
pp. 1881-1886
Author(s):  
Seong-Ho Ha ◽  
Young-Ok Yoon ◽  
Bong-Hwan Kim ◽  
Hyun-Kyu Lim ◽  
Sung-Hwan Lim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Oxide Film ◽  
Phase Diagrams ◽  
Film Formation ◽  
Mg Alloy ◽  
Short Term ◽  
Spinel Formation ◽  
Transmission Electron ◽  
Significant Difference

In this study, using transmission electron microscopy and phase diagrams from thermodynamic calculations, we investigated the oxide film formation of Al–7.5 mass%Mg alloy containing Ca traces during short-term oxidation in terms of the thermodynamic stability and multi-element oxides by inter-diffusion based on the results of analysis for the oxide film. For the oxidation test at 515 ˚C, for 1 h, its results showed that there is no significant difference between the Ca-added and Ca-free Al–7.5 mass%Mg alloys was observed, while further exposure caused the Ca-free alloy to gain significant weight. Based on the standard Gibbs free energy for oxide production calculated in this study, CaO was the most preferential product among the single metal oxides examined. As per calculations for MgAl2O4-spinel formation reactions, the spinel formation from MgO was thermodynamically the most favorable. According to the phase diagrams calculated in this study, various multi-element oxides including Ca could possibly form in the oxide layer of Ca-added alloy. The analysis results of transmission electron microscopy confirmed that MgO is the primary oxide in the Al–Mg binary alloys. In oxidation tests conducted for less than 1 h, the spinel was rarely found. The outmost areas of oxide layers correspond to MgO and CaO in Ca-free and Ca-added alloys, respectively. However, in the Ca-added alloy, the inner layer contains certain amounts of Ca, Al, and Mg.

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