Effect of the Long Natural Aging on the Precipitation Sequence in Al-Mg-Si Alloy

2014 ◽  
Vol 893 ◽  
pp. 375-380 ◽  
Author(s):  
Zakaria Boumerzoug ◽  
Ines Hamdi
Keyword(s):  
Differential Scanning Calorimetry ◽  
Artificial Aging ◽  
Natural Aging ◽  
Precipitation Sequence ◽  
Precipitation Behavior ◽  
Scanning Calorimetry ◽  
Hardening Mechanism ◽  
Negative Effect

In this study, the effect of the long natural aging on the precipitation sequence of Al-Mg-Si alloy was investigated by differential scanning calorimetry and hardness examinations. This investigation revealed that the natural aging has a negative effect on the artificial aging. The reason behind the influence of natural aging on precipitation behavior of the Al-Mg-Si alloy is assumed to be the formation of clusters and G.P. zone during natural aging. The hardening mechanism during artificial aging was explained.

scholarly journals Effect of Cold Rolling on Cluster(1) Dissolvability during Artificial Aging and Formability during Natural Aging in Al-0.6Mg-1.0Si-0.5Cu Alloy

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 92
Author(s):  
Naoto Kirekawa ◽  
Kaisei Saito ◽  
Minho O ◽  
Equo Kobayashi
Keyword(s):  
Cold Rolling ◽  
Artificial Aging ◽  
Cluster Formation ◽  
Solution Treatment ◽  
Natural Aging ◽  
Tensile Tests ◽  
Scanning Calorimetry ◽  
Hardness Tests ◽  
Negative Effect ◽  
Cold Rolled

Natural aging after solution treatment has a negative effect on the precipitation strengthening of Al–Mg–Si alloys since Cluster(1) formed at a room temperature cannot be dissolved or transformed into precipitates during artificial aging at 170 °C. In this study, cold rolling is focused on as an alternative solution to pre-aging, which is a conventional method to prevent Cluster(1) formation. It is known that excess vacancies are necessary for cluster formation. Cold rolling suppresses cluster formation because excess vacancies disappear at dislocations introduced by cold rolling. In addition, it is expected that cold rolling accelerates the precipitation behavior because the diffusion of solute atoms is promoted by introduced lattice defects. The transition of Cluster(1) was evaluated by Micro Vickers hardness tests, tensile tests, electrical conductivity measurements and differential scanning calorimetry analyses. Results showed the negative effect of natural aging was almost suppressed in 10% cold-rolled samples and completely suppressed in 30% cold-rolled samples since Cluster(1) dissolved during artificial aging at 170 °C due to lowering of the temperature of Cluster(1) dissolution by cold rolling. It was found that the precipitation in cold-rolled samples was accelerated since the hardness peak of 10% cold-rolled samples appeared earlier than T6 and pre-aged samples.

The Natural Aging Effect on the Activation Energy of the Precipitation Processes in the Al-Mg-Si Alloy

2016 ◽  
Vol 723 ◽  
pp. 27-31
Author(s):  
Ines Hamdi ◽  
Zakaria Boumerzoug
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Natural Aging ◽  
Aging Effect ◽  
Stable Phase ◽  
Precipitation Process ◽  
Precipitation Sequence ◽  
Scanning Calorimetry ◽  
Kissinger Model ◽  
Precipitated Phases

The precipitation sequence of an Al-Mg-Si alloy depends on many parameters. In this study the natural aging effect on the activation energy of the precipitation sequence in the Al-Mg-Si alloy have been investigated by differential scanning calorimetry (DSC). The precipitation sequence of an Al-Mg-Si alloy has been established. The activation energy of the precipitation process was calculated using Kissinger model. The results obtained using this method showed a change in the activation energy for all precipitated phases. The activation energy of the metastable phases (β″ and β′) and the stable phase β formation in the Al-Mg-Si alloy aged at room temperature have been determined.

Complementarity of Atom Probe, Small Angle Scattering and Differential Scanning Calorimetry for the Study of Precipitation in Aluminium Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 926-932 ◽  
Author(s):  
Frédéric de Geuser ◽  
Thomas Dorin ◽  
Williams Lefebvre ◽  
Baptiste Gault ◽  
Alexis Deschamps
Keyword(s):  
Differential Scanning Calorimetry ◽  
Small Angle ◽  
Atom Probe Tomography ◽  
Aluminium Alloys ◽  
Atom Probe ◽  
Small Angle Scattering ◽  
Precipitation Behavior ◽  
Scanning Calorimetry ◽  
Model Free ◽  
Angle Scattering

Two examples of precipitation studies (in Al-Li-Cu and Al-Li-Mg alloys) are shown to demonstrate the complementarity of atom probe tomography, small-angle-scattering and differential scanning calorimetry for precipitation studies. It will be used to unravel an unexpected two-step precipitation behavior of T1in Al-Li-Cu and to ascertain precipitates size in Al-Li-Mg. through a model free comparison between atom probe and SAXS.

Study on the Precipitation Sequence of Aged NCu30-4-2-1 Alloy by DSC

2014 ◽  
Vol 1061-1062 ◽  
pp. 35-38
Author(s):  
Yun Long Ai ◽  
Xiao Rui Shen ◽  
Wei Hua Chen ◽  
Yao Hui Xie
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Supersaturated Solid Solution ◽  
Aging Treatment ◽  
Holding Time ◽  
Precipitation Sequence ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Different Temperatures ◽  
Block Distribution

NCu30-4-2-1 alloy was handled by solid solution at 950°Cfor 2h and then taking aging treatment at different temperatures and holding time. The microstructural evolution of NCu30-4-2-1 alloy in the process of aging treatment was investigated by metallographic microscope, X-ray diffractometer and differential scanning calorimetry. The results show that the phases of as-cast NCu30-4-2-1 alloy is composed by dendritic α-Ni-based solid solution and β-Ni3Si. After solid solution and aging treatment, the block distribution β-Ni3Si dissolves and many small granular dispersed distribution β'-Ni3Si precipitate out. With the increase of aging temperature and holding time, metastable β' tends to transform into stable β-Ni3Si. The precipitation sequence of aged NCu30-4-2-1alloy is supersaturated solid solution of α-Ni, GP zone, β'-Ni3Si and β-Ni3Si.

Effects of Zn Addition and Aging Condition on Serrated Flow in Al-Mg Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 483-488 ◽  
Author(s):  
Katsushi Matsumoto ◽  
Yasuhiro Aruga ◽  
Hidemasa Tsuneishi ◽  
Hikaru Iwai ◽  
Masataka Mizuno ◽  
...  
Keyword(s):  
Artificial Aging ◽  
Flow Behavior ◽  
Natural Aging ◽  
Atom Probe ◽  
Mg Alloys ◽  
Scanning Calorimetry ◽  
Serrated Flow ◽  
Zn Addition ◽  
Al Mg Alloys ◽  
Zn Alloys

The serrated flow phenomena in Al-Mg alloys with and without Zn were investigated after aging on several conditions, focusing on the role of precipitates. Al-6mass%Mg-0~3mass%Zn alloys were solution treated at 753~803K, quenched, and then aged at room temperature. Further artificial aging at 323~573K for 86.4ks was performed for some of them after natural aging for 2.6Ms. The serrated flow behavior was evaluated by tensile test. Microstructure was characterized by differential scanning calorimetry, transmission electron microscopy, atom probe tomography, and positron annihilation lifetime spectroscopy. The increase in the amount of Zn addition and the natural aging time lead to a delayed onset of serrated flow. The artificial aging at higher temperatures after natural aging, on the other hand, decreases the onset strain. A large number of small coherent Zn-Mg clusters are formed during natural aging in the Al-Mg-Zn alloys, which are transformed to the larger incoherent meta-stable precipitates during subsequent artificial aging. These results suggest that the mechanism of interfering with serrated flow is related to the vacancy trapping effect, which is enhanced by the coherent clusters.

Pre-Aging and Maturing Effects on the Precipitation Hardening of an Al-Mg-Si Alloy

2010 ◽  
Vol 297-301 ◽  
pp. 68-73
Author(s):  
T. Abid ◽  
A. Boubertakh ◽  
S. Hamamda
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Artificial Aging ◽  
Precipitation Hardening ◽  
Natural Aging ◽  
Undesirable Effect ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Later Phase ◽  
Scanning Electron

The effect of pre-aging and maturing at room temperature on the hardening response of an Al-Mg-Si alloy is investigated using differential scanning calorimetry (DSC), hardness measurements (Hv) and scanning electron microscopy (SEM).Two experimental conditions are examined. First, natural aging for different times (3 weeks and 1 month) followed by artificial aging at 180°C as a function of time. Second, pre-aging at temperatures in the range 75-100°C followed by artificial aging at 180°C after natural aging for the same periods. The present results indicate that the effect of the pre-aging just after the heating and quenching is used in order to correct the undesirable effect of aging at room temperature. However, during the artificial aging, the alloy hardening becomes faster. Aged samples which have already undergone pre-aging and maturing reveal the precipitation of ''phase. This later phase has the highest hardness value.

Effect of Pre-Straining and Natural Aging on the Hardening Response during Artificial Aging of EN AW 6082 and Lead Free EN AW 6023 Aluminium Alloys

2019 ◽  
Vol 952 ◽  
pp. 82-91
Author(s):  
Martin Fujda ◽  
Miloš Matvija ◽  
Peter Horňak
Keyword(s):  
Aluminium Alloys ◽  
Artificial Aging ◽  
Solution Treatment ◽  
Natural Aging ◽  
Age Hardening ◽  
Aging Effects ◽  
Β Phase ◽  
Transmission Electron ◽  
Negative Effect ◽  
Microscopy Characterization

In order to study the pre-straining and natural aging effects on the age-hardening response of EN AW 6082 and EN AW 6023 aluminium alloys during artificial aging at 170°C, the pre-straining by 5% was performed immediately after solution treatment of alloys at 550°C and subsequent quenching. The age-hardening response during artificial aging applied after various natural aging time (from 0.1 to 5 000 hours) was investigated using Vickers microhardness measurements and transmission electron microscopy characterization. It was found that pre-straining of quenched alloys state caused a dislocation density increasing in solid solution, which resulted in an immediate microhardness increase of alloys. During the subsequent natural aging of EN AW 6082 alloy, its microhardness increased right after alloy quenching and pre-straining, but only to the values obtained for the unstrained alloy state. On the contrary, the hardness of pre-straining EN AW 6023 alloy that is alloyed by Sn did not increase either after 10 hours of natural aging. This phenomenon is attributed to the effect of Sn on suppression of the strengthening clusters formation. The hardness of alloys increased greatly during artificial aging after pre-straining and natural aging due to accelerating the formation of coherent β″-phase particles. The negative effect of natural aging on the maximum age-hardening response obtained during alloys artificial aging had been observed for most of the pre-strained and naturally aged alloys states, with exception of EN AW 6023 alloy states that were pre-strained and shortly naturally aged (up to 100 hours).

Joint differential scanning calorimetry, electrical resistivity, and microhardness study of aging in two AlCuMg alloys

2003 ◽  
Vol 18 (7) ◽  
pp. 1522-1527 ◽  
Author(s):  
G. Riontino ◽  
M. Massazza ◽  
S. Abis
Keyword(s):  
Differential Scanning Calorimetry ◽  
Electrical Resistivity ◽  
Artificial Aging ◽  
Microhardness Study ◽  
Scanning Calorimetry ◽  
Zone Formation ◽  
Intermediate Phases

Two age-hardenable AlCuMg alloys (Cu 4.5 wt.% and Cu/Mg ratios of 2.5 and 8) were studied by electrical resistivity, differential scanning calorimetry, and microhardness measurements during natural and artificial aging at 110 °C. The results were interpreted in terms of Guinier–Preston/Guinier–Preston–Bagariatskij zone formation followed by a modification in θ″ and S″ intermediate phases.

Precipitation Processes in Mg-Y-Nd Alloys

2013 ◽  
Vol 334-335 ◽  
pp. 155-160 ◽  
Author(s):  
Martin Vlach ◽  
Bohumil Smola ◽  
Hana Císařová ◽  
Ivana Stulíková
Keyword(s):  
Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Precipitation Sequence ◽  
Scanning Calorimetry ◽  
Solution Treated ◽  
Phase Type ◽  
Precipitation Processes ◽  
The Matrix ◽  
Apparent Activation Energies ◽  
Type Decomposition

Successive precipitation processes in solution treated Mg3Y3Nd alloy were studied by electrical resistometry, by differential scanning calorimetry and by microhardness. The results were compared to those in the commercial WE43 alloy. Five various phases known from the Mg-Gd-and Mg-Nd-type decomposition sequences form, dissolute or transform in the Mg3Y3Nd alloy. The main difference in the WE43 precipitation sequence is the absence of the β1 phase particles. Electron microscopy confirmed that not the phase type of hardening particles but their morphology, size and orientation to the matrix determine the hardening effectiveness. Differential scanning calorimetry revealed exothermic effects connected to precipitation processes. Apparent activation energies of individual precipitation processes correspond to those in the MgTbNd and in MgNd alloys.

Simulation of Natural Aging in Al-Mg-Si Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 468-473 ◽  
Author(s):  
Thomas Weisz ◽  
Piotr Warczok ◽  
Thomas Ebner ◽  
Ahmad Falahati ◽  
Ernst Kozeschnik
Keyword(s):  
Experimental Investigation ◽  
Room Temperature ◽  
Artificial Aging ◽  
Cluster Formation ◽  
Natural Aging ◽  
Room Temperature Aging ◽  
Negative Effect ◽  
Aging Mechanisms ◽  
Microalloying Elements ◽  
Temperature Aging

Natural aging during storage of Al-Mg-Si alloys at room temperature can significantly reduce the maximum strengthening potential (T6) during artificial aging and, therefore, is a key topic in aluminium research and industry. Many different strategies to understand and reduce the negative effect of natural aging have been investigated during the last decades, including analysis of different thermal pre-treatments and considering the effect of different microalloying elements. From these investigations, the vacancy evolution and the formation of clusters containing Mg and Si were found to be the governing aging mechanisms behind natural aging. In this work, we present a model to simulate and predict the behavior of these alloys when subjected to room temperature aging after solutionizing and demonstrate the effects of different thermal routes and chemical composition variations. In the implemented model, the evolution of excess quenched-in vacancies and the effect of solute vacancy traps are considered. Special emphasis is placed on co-cluster formation and its contribution to strengthening. The thermokinetic software MatCalc is used for the simulations and the results of the simulations are validated by experimental investigation.

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