scholarly journals Microstructure development during thermomechanical treatment of Al-Mg-Si alloy

2002 ◽  
Vol 38 (3-4) ◽  
pp. 153-162 ◽  
Author(s):  
Z. Martinova ◽  
G. Zlateva
Keyword(s):  
Electrical Conductivity ◽  
Thermomechanical Treatment ◽  
Artificial Aging ◽  
Cold Deformation ◽  
Natural Aging ◽  
Tensile Tests ◽  
Prolonged Storage ◽  
Recovery Processes ◽  
Transmission Electron ◽  
Lower Aging Temperature

The effect of natural aging and 95% cold deformation on the microstructure evolution and aging characteristics in commercial Al - 1 mass % Mg2Si alloy subjected to thermomechanical treatment (TMT) was examined. Transmission electron microscopy observations, tensile tests and electrical conductivity measurements were carried out in order to correlate microstructural features to properties on each TMT step. It was established that pre-aging at room temperature affected the morphology of dislocation structure induced by next cold deformation. The observed transition from cellular to homogenous dislocation distribution was explained by the different stability of zones produced by pre-aging of different duration. Natural aging suppressed recovery processes during post-deformation artificial aging, especially after prolonged storage after quenching and at lower aging temperature. It influenced the morphology of precipitates produced by post deformation artificial aging also. The overall effect of TMT involving prior-deformation natural aging in the scheme, on hardness, tensile properties and electrical conductivity is discussed based on experimental microstruture observations.

The Effect of Deformation on the Work Hardening Behaviour after Aging of Two Commercial Al-Mg-Si Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 261-266 ◽  
Author(s):  
Michal Kolar ◽  
Ketill Olav Pedersen ◽  
Sverre Gulbrandsen-Dahl ◽  
Thiemo Brüggemann ◽  
Knut Marthinsen
Keyword(s):  
Aging Time ◽  
Work Hardening ◽  
Natural Aging ◽  
Tensile Tests ◽  
Engineering Strain ◽  
Transmission Electron ◽  
Aging Response ◽  
Heat Treated ◽  
Work Hardening Rate ◽  
Commercial Aluminium

In order to investigate the effect of deformation on the aging response of Al-Mg-Si alloys, a series of tensile tests have been designed and carried out on two commercial aluminium alloys, i.e. AA6060 and AA6082. Extruded and solution heat treated specimens were pre-deformed 0%, 5%, and 10% (engineering strain), respectively followed by natural aging (NA). It was observed that the work-hardening rate increases with prolonged natural aging time and decreases with increasing pre-deformation prior to natural aging. The most significant effect of deformation was obtained for T4 temper i.e. after 1000 and 10000 minutes NA for the 6082 and 6060 alloy, respectively, when the amount of pre-deformation is 10%. A remarkable difference in work-hardening rate at the level of small plastic strains was observed compared to that of the material naturally aged for only 10 minutes. In addition to the tensile tests, transmission electron microscopy (TEM) has been used to characterize dislocation evolution for various combinations of pre-deformation and aging time.

Aging hardening characteristic and electrical conductivity of Cu-Cr-Zr-Mo in situ composite

2016 ◽  
Vol 23 (6) ◽  
pp. 599-603
Author(s):  
Song Wang ◽  
Tingting Zheng ◽  
Ming Xie ◽  
Yongtai Chen ◽  
Jiming Zhang
Keyword(s):  
Electrical Conductivity ◽  
Cold Deformation ◽  
Aging Treatment ◽  
Cold Drawing ◽  
Secondary Phase ◽  
Comprehensive Properties ◽  
Dispersed Particles ◽  
Transmission Electron ◽  
Aging Hardening

AbstractCu-0.85Cr-0.5Zr-0.5Mo in situ composite was prepared by continuous casting, cold drawing, and aging treatment. By means of the analysis of microhardness, electrical conductivity, and transmission electron microscopy, the aging characteristics and microstructures of the in situ composite were investigated at different aging temperatures and aging times after cold deformation. The results show that the Cu-0.85Cr-0.5Zr-0.5Mo in situ composite has an excellent combination of the microhardness and electrical conductivity aged at 500°C for 4 h, and the microhardness and electrical conductivity reach 171 HV and 81.3% IACS, respectively. Small dispersed particles could strongly pin dislocations and stabilize the substructure from deformation. The main strengthening mechanisms for the in situ composite alloy are the work hardening and the secondary phase or interface strengthening. It was suggested that cold deformation before aging treatment can accelerate the precipitation of the secondary phase and improve the comprehensive properties of the Cu-Cr-Zr-Mo in situ composite.

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).

scholarly journals Aging Response and Precipitation Behavior after 5% Pre-Deformation of an Al-Mg-Si-Cu Alloy

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1422 ◽  
Author(s):  
Shuoxun Jin ◽  
Tungwai Ngai ◽  
Liejun Li ◽  
Shian Jia ◽  
Tongguang Zhai ◽  
...  
Keyword(s):  
Yield Strength ◽  
Artificial Aging ◽  
Natural Aging ◽  
Negative Influence ◽  
Peak Hardness ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Peak Aging ◽  
Peak Aged ◽  
Deformation Treatment

In this study, Al-1.00 Mg-0.65 Si-0.24 Cu alloy was solution heat-treated, water-quenched, and then pre-deformed for 5% before aging. The peak hardness and yield strength of the pre-deformed sample with subsequent artificial aging were similar to that of a T6 condition sample. It was also found that the pre-deformation treatment could inhibit the negative influence of natural aging to some degree. After seven days of natural aging, the pre-deformed sample obtained better peak hardness and yield strength upon artificial aging than the sample without pre-deformation. In addition, the pre-deformation treatment could reduce 50% of the artificial aging time to reach the peak aging condition compared with T6 treatment. For the peak aged condition in the pre-deformed sample, transmission electron microscopy (TEM) observation found two types of precipitates exhibited along the dislocations besides the β″ precipitates in the Al matrix. Both precipitates had disordered atomic arrangements on the ordered subcell (Si network). The disordered precipitates occupied a number of Mg and Si atoms, resulting in less β″ precipitates formed during artificial aging at 180 °C.

Effect of Natural Aging of 6xxx Series Extrusions on the Energy Absorbance Capacity

2016 ◽  
Vol 877 ◽  
pp. 315-321 ◽  
Author(s):  
Athanasios Vazdirvanidis ◽  
George Pantazopoulos ◽  
Anagnostis Toulfatzis ◽  
Andreas Rikos ◽  
Dimitrios Manolakos
Keyword(s):  
Artificial Aging ◽  
Natural Aging ◽  
Tensile Tests ◽  
Maximum Energy ◽  
Intergranular Cracking ◽  
Static Compression ◽  
Aging Kinetics ◽  
6Xxx Series ◽  
Quasi Static Compression ◽  
Scanning Electron

In this study the influence of natural aging in energy absorbance capacity of 6xxx series extruded profiles after artificial aging is examined by means of optical and scanning electron microscopy, quasi-static compression and tensile tests. Mobile quenched-in vacancies are found to play an important role in aging kinetics and formation of precipitate free zones (PFZs) which govern both the observed fracture modes and the resulting strength of the material signifying their important effect when maximum energy absorbance is desired. It is shown that fracture toughness of naturally aged samples is equivalent or higher compared to that of directly aged samples due to restriction of intergranular cracking.

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.

scholarly journals Effect of Ni/Si Mass Ratio and Thermomechanical Treatment on the Microstructure and Properties of Cu-Ni-Si Alloys

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2076 ◽  
Author(s):  
Jiang Li ◽  
Guojie Huang ◽  
Xujun Mi ◽  
Lijun Peng ◽  
Haofeng Xie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Transmission Electron Microscopy ◽  
Thermomechanical Treatment ◽  
Theoretical Calculations ◽  
High Strength ◽  
Atom Probe ◽  
Mass Ratio ◽  
Microstructure And Properties ◽  
Transmission Electron

The effect of the Ni/Si mass ratio and combined thermomechanical treatment on the microstructure and properties of ternary Cu-Ni-Si alloys is discussed systematically. The Cu-Ni-Si alloy with a Ni/Si mass ratio of 4–5 showed good comprehensive properties. Precipitates with disc-like shapes were confirmed as the Ni2Si phase with orthorhombic structure through transmission electron microscopy, high-resolution transmission electron microscopy, and 3D atom probe characterization. After the appropriate thermomechanical treatment, the studied alloy with a Ni/Si mass ratio of 4.2 exhibited excellent mechanical properties: a hardness of 290 HV, tensile strength of 855 MPa, yield strength of 782 MPa, and elongation of 4.5%. Compared with other approaches, the thermomechanical treatment increased the hardness and strength without sacrificing electrical conductivity. Theoretical calculations indicated that the high strength was primarily attributed to the Orowan precipitation strengthening and secondarily ascribed to the work hardening, which were highly consistent with the experimental results. The appropriate Ni/Si mass ratio with a low content of Ni and Si atoms shows high strength and excellent electrical conductivity through combined thermomechanical treatment. This work provides a guideline for the design and preparation of multicomponent Cu-Ni-Si-X alloys with ultrahigh strength and excellent electrical conductivity.

scholarly journals Comparison of long-term natural aging to artificial aging in Duralumin

2020 ◽  
Vol 326 ◽  
pp. 04007
Author(s):  
Magali Brunet ◽  
Benoit Malard ◽  
Nicolas Ratel-Ramond ◽  
Christophe Deshayes ◽  
Bénédicte Warot-Fonrose ◽  
...  
Keyword(s):  
Aluminium Alloys ◽  
Artificial Aging ◽  
Solution Treatment ◽  
Natural Aging ◽  
Tensile Tests ◽  
Aged Alloy ◽  
Early Failure ◽  
Long Time ◽  
Aging Conditions

The understanding of long-term aging of aeronautical materials, in particular aluminium alloys used in the fuselage and structure of aircraft is of extreme importance for airline fleets. In this work, a plate from an old aircraft (Breguet) was retrieved and studied in terms of microstructure and mechanical properties. A comparison was made between this naturally-aged alloy and a modern alloy on which different artificial aging conditions were applied. The old alloy exhibits a precipitation of θ-Al2Cu at grain boundaries and of Ω-Al2Cu on dispersoids. This non-expected nanostructure for an alloy in T4 state was attributed to the heat that the plate experienced during the aircraft cycles. However, it is shown that this aging is reversible (after a solution treatment). Moreover, the very long time of outdoors exposure seems to have caused intergranular corrosion causing the early failure during tensile tests on some of the specimens. The artificial aging (low temperature, 100°C for up to 10,000h) applied on the modern 2017A alloy did not allow to reproduce the nanostructure of the old plate, meaning that isothermal conditions for artificial aging might not be appropriate in this case.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

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