TEM Observation for Precipitates Structure of Aged Al-Zn-Mg Series Al Alloys Addition of Cu or Ag

2014 ◽  
Vol 922 ◽  
pp. 791-794
Author(s):  
Katsumi Watanabe ◽  
Susumu Ikeno ◽  
Tomoo Yoshida ◽  
Satoshi Murakami ◽  
Kenji Matsuda
Keyword(s):  
Mechanical Property ◽  
Aluminum Alloys ◽  
High Strength ◽  
Al Alloys ◽  
Mg Alloy ◽  
Age Hardening ◽  
Number Density ◽  
Maximum Hardness ◽  
Aging Behavior ◽  
Peak Aged

Al-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg alloy, were prepared to compare the effect of the additional elements on the aging behavior. Ag or Cu added alloy showed higher maximum hardness than Ag or Cu free alloy. The η’ phase were observed in all alloys peak-aged at 423K. According to addition of Ag or Cu, the number density of the precipitates increased than Ag or Cu free alloy.

TEM Observation of Precipitate Structures in Al-Zn-Mg Alloys with Additions of Cu/Ag

2014 ◽  
Vol 794-796 ◽  
pp. 985-987 ◽  
Author(s):  
Katsumi Watanabe ◽  
Kenji Matsuda ◽  
Susumu Ikeno ◽  
Tomoo Yoshida ◽  
Satoshi Murakami
Keyword(s):  
Mechanical Property ◽  
Aluminum Alloys ◽  
Base Alloy ◽  
High Strength ◽  
Mg Alloy ◽  
Age Hardening ◽  
Number Density ◽  
Maximum Hardness ◽  
Aging Behavior ◽  
Peak Aged

Al-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg alloy, were prepared to compare the effect of the additional elements on the aging behavior. The content of Ag and Cu were 0.2at.% and the same as, respectively. Ag or Cu added alloy showed higher maximum hardness than base alloy. The particle shape and rod shape precipitates were observed in all alloys peak-aged at 423K. According to addition of Ag or Cu, the number density of the precipitates increased higher than that of base alloy.

scholarly journals Tem Observation Of Precipitate Structures In Al-Zn-Mg Alloys With Additions Of Cu/Ag

2015 ◽  
Vol 60 (2) ◽  
pp. 977-979 ◽  
Author(s):  
K. Watanabe ◽  
K. Matsuda ◽  
S. Ikeno ◽  
T. Yoshida ◽  
S. Murakami
Keyword(s):  
Mechanical Property ◽  
Aluminum Alloys ◽  
Base Alloy ◽  
High Strength ◽  
Mg Alloy ◽  
Age Hardening ◽  
Number Density ◽  
Maximum Hardness ◽  
Aging Behavior ◽  
Peak Aged

AbstractAl-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg alloy, were prepared to compare the effect of the additional elements on the aging behavior. The content of Ag and Cu were 0.2at.% and the same as, respectively. Ag or Cu added alloy showed higher maximum hardness than base alloy. The particle shape and rod shape precipitates were observed in all alloys peak-aged at 423K. According to addition of Ag or Cu, the number density of the precipitates increased higher than that of base alloy.

Effect of the Zn/Mg Ratio on Microstructure and Mechanical Properties in Al-Zn-Mg Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 479-482 ◽  
Author(s):  
Masatomo Nishi ◽  
Kenji Matsuda ◽  
Naoya Miura ◽  
Katsumi Watanabe ◽  
Susumu Ikeno ◽  
...  
Keyword(s):  
High Strength ◽  
Hardness Measurement ◽  
Tensile Tests ◽  
Mg Alloys ◽  
Mg Alloy ◽  
Age Hardening ◽  
Peak Hardness ◽  
Number Density ◽  
Peak Aged Condition ◽  
Peak Aged

It is well know that the 7000 series Al-Zn-Mg alloy has good age hardening ability and high strength among commercial aluminum alloys. In this study, hardness measurement, tensile test, SEM and TEM observation have been performed in order to understand the effect of the Zn/Mg ratio on age hardening behaviour in Al-Zn-Mg alloys. It was seen from hardness measurement that the peak hardness increased with increasing amount of Zn and Mg. Tensile tests were performed for the samples of peak aged condition. It was seen that UTS increased with increasing amount of the Zn and Mg. The elongation decreased with increasing the amount of the Zn and Mg. Intregranular fracture was observed in alloys with low amount of Zn and Mg.Transgranular fracture was observed with high amount of Zn and Mg alloy. TEM observation was performed for peak aged samples. The size of precipitates became finer and the number density increased with increasing Zn and Mg contents.T’ Phase and h1 phase were observed in low Zn/Mg alloy. The h’ phase was observed in high Zn/Mg alloy.

Effect of Zn/Mg on Age Hardening Behavior in 7000 System Al Alloys

2014 ◽  
Vol 922 ◽  
pp. 549-552
Author(s):  
Masatomo Nishi ◽  
Naoya Miura ◽  
Katsumi Watanabe ◽  
Susumu Ikeno ◽  
Tomoo Yoshida ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Tensile Test ◽  
High Strength ◽  
Hardness Measurement ◽  
Age Hardening ◽  
Number Density ◽  
Aged Condition ◽  
Hardening Behavior ◽  
Peak Aged Condition ◽  
Peak Aged

7000 System Al has been known as one of the aluminum alloys with the good age hardening ability and the high strength among commercial aluminum alloys. [1]In this study, hardness measurement, tensile test, SEM observation and TEM observation have been performed in order to understand the effect of Zn/Mg ratio on age hardening behaviour in Al-Zn-Mg alloys . It can be seen from hardness measurement that the alloy containing higher Zn and Mg contents became hard. Tensile test was performed for the samples of peak aged condition. It can been seen that the alloy containing higher Zn and Mg increases the tensile strength of the alloy though decrease of the elongation were observed a typical intergranular fracture. TEM observation was performed for peak aged samples. The size of precipitates became finer and the number density increased with increasing Zn and Mg contents.

Retrogression and Re-aging Heat Treatment: AA7XXX Aluminum Alloys

2019 ◽  
Author(s):  
V. Anil Kumar ◽  
S. Arjun ◽  
R.K. Gupta ◽  
P.V. Venkitakrishnan
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloys ◽  
Industrial Applications ◽  
Age Hardening ◽  
Large Cross Section ◽  
Structural Applications ◽  
The Matrix ◽  
Peak Aged ◽  
Aged Temper ◽  
Short Time

Retrogression and re-aging (RRA) treatment was introduced to increase the stress corrosion cracking (SCC) resistance while retaining the strength attainable in T6 (peak aged) temper. Retrogression is a short-term heat treatment at an elevated temperature wherein a partial dissolution of metastable precipitates occurs, which are responsible for the hardening. During the next step, the material is re-aged in the regime of typical age hardening parameters to restore the strength with improved ductility. Response of RRA treatment has been reported on AA7XXX series Aluminum alloys such as AA7075, AA7050, AA7150, AA7049, and AA7010. Studies have been done on the effect of RRA on microstructure, mechanical properties such as tensile and hardness, corrosion, exfoliation corrosion, and SCC resistance by various researchers. The key characteristic of RRA is retrogression, which makes the re-precipitation in the matrix and coarsening of grain boundary precipitates such as MgZn2, η′. The retrogression treatment however requires high temperature and a short time, which limits the industrial application of RRA, especially in the heat treatment of the components with large cross section, due to the inherent thermal conductivity limitations. Hence, further work needs to be done in this area to apply this specialized heat treatment for industrial applications. This article brings out a comprehension of the changes in microstructure, tensile properties, and corrosion resistance of the various commonly used AA7XXX Aluminum alloys in structural applications with RRA heat treatment. The future scope of the work in RRA heat treatment is also discussed in this article.

Key Microstructural Features Responsible for Improved Stress Corrosion Cracking Resistance and Weldability in 7xxx Series Al Alloys Containing Micro / Trace Alloying Additions

2006 ◽  
Vol 519-521 ◽  
pp. 315-320 ◽  
Author(s):  
A.K. Mukhopadhyay ◽  
K. Satya Prasad ◽  
Vikas Kumar ◽  
G. Madhusudhan Reddy ◽  
S.V. Kamat ◽  
...  
Keyword(s):  
Quantitative Data ◽  
Microstructural Analysis ◽  
High Strength ◽  
Al Alloys ◽  
The Other ◽  
Alloying Additions ◽  
Cu Alloys ◽  
Medium Strength ◽  
Retrogression And Reaging ◽  
Peak Aged

The commercial 7xxx series Al alloys are based on medium strength Al-Zn-Mg and high strength Al-Zn-Mg-Cu systems. The medium strength alloys are weldable, whilst the high strength alloys are nonweldable. On the other hand, the Cu-free, weldable alloys suffer from poor SCC resistance. It is the purpose of this article to provide quantitative data and microstructural analysis to demonstrate that small additions of either Ag or Sc to Al-Zn-Mg and Al-Zn-Mg-Cu alloys bring about very significant improvement in SCC resistance and weldability, respectively. The improvement in SCC resistance of the Cu-bearing alloys due to over aging and retrogression and reaging (RRA) is further discussed in light of a similar improvement in the SCC resistance of these alloys, when peak aged, due to Ag and Sc additions.

scholarly journals Effects of Mg Addition and Pre-Aging on the Age-Hardening Behavior in Al-Mg-Si

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1046 ◽  
Author(s):  
JaeHwang Kim ◽  
Jiwoo Im ◽  
Minyoung Song ◽  
Insu Kim
Keyword(s):  
Early Stage ◽  
Natural Aging ◽  
Age Hardening ◽  
Number Density ◽  
Hardening Behavior ◽  
Transmission Electron ◽  
Alloy Hardness ◽  
Peak Aged ◽  
Mg Addition ◽  
Cluster 2

Two types of nanoclusters, Cluster (1) and Cluster (2), formed at around room temperature and 100 °C, respectively, affect the age-hardening behavior in Al-Mg-Si alloys. Formation of Cluster (1) during natural aging (NA) is more accelerated in the high-Mg (9M10S) alloy than in the low-Mg (3M10S) alloy. Hardness at the early stage of two-step aging at 170 °C is not increased for the natural aging samples. On the other hand, hardness is directly increased for the pre-aged (PA) specimens. Furthermore, the formation of Cluster (1) during natural aging is suppressed by the formation of Cluster (2) during pre-aging at 100 °C. To understand the effects of heat treatment histories and Mg contents on the microstructure, transmission electron microscopy (TEM) was utilized. All the images were obtained at (001) plane, and peak aged samples with different heat treatments were used. Lower number density of precipitates is confirmed for the natural aging samples compared with the single-aged and pre-aged specimens. A higher number density of precipitates is confirmed for 9M10S in comparison to 3M10S. Hardness results correspond well to the TEM images.

Detection of Quench Induced Precipitation in Al Alloys by Dilatometry

2016 ◽  
Vol 877 ◽  
pp. 147-152 ◽  
Author(s):  
Benjamin Milkereit ◽  
Michael Reich ◽  
Olaf Kessler
Keyword(s):  
Cooling Rate ◽  
High Strength ◽  
Al Alloys ◽  
Age Hardening ◽  
Controlled Cooling ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
Precipitation Behaviour ◽  
In Situ Detection

Quenching is a critical step during the strengthening age hardening of Aluminium alloys. To obtain optimal technological results, parts should be quenched with the upper critical cooling rate. The precipitation behaviour of Al alloys during cooling from solution annealing and thereby the critical cooling rates are typically investigated by in-situ measurements with differential scanning calorimetry (DSC). Conventional DSCs are limited at cooling rates below 10 Ks-1. Unfortunately, medium to high strength Al alloys typically have critical cooling rates between 10 and some 100 Ks-1. Recently it was shown that dilatometry is generally able for in-situ detection of precipitation in Al alloys. Dilatometry allows controlled cooling up to some 100 Ks-1 and therefore covers the cooling rate range relevant. In this work, we aim to show up and discuss possibilities and limitations of dilatometric detection of quench induced precipitates in 2xxx, and 7xxx Al alloys. The basic method will be presented and results will be compared with DSC work.

Aging Behaviour of Aluminium Alloys after Severe Plastic Deformation

2006 ◽  
Vol 519-521 ◽  
pp. 1485-1492 ◽  
Author(s):  
Z. Horita
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strength ◽  
Age Hardening ◽  
Precipitation Process ◽  
Al Alloy ◽  
Metallic Materials ◽  
Aging Behavior ◽  
Angular Pressing ◽  
Transmission Electron

The process of severe plastic deformation (SPD) makes it possible to reduce the grain size to the submicrometer or nanometer range in many metallic materials. When the SPD process is applied to age hardenable alloys, it may also be possible to control aging behavior. In this study, a technique of equal-channel angular pressing (ECAP) is used as an SPD process and aging behavior is examined on the three selected Al alloy systems such as Al-Ag, Al-Mg-Si and Al-Si-Ge. The microstructures are observed using transmission electron microscopy and the mechanical properties including hardness are measured. It is shown that the SPD process introduces unusual phenomena in the precipitation process and there should be a potential for enhancement of strength over the conventional age-hardening process or for improvement of ductility while keeping the high strength.

Studies of precipitate rich-zones on grain boundaries of Al-Mg-Si alloys after aging

1978 ◽  
Vol 36 (1) ◽  
pp. 642-643
Author(s):  
Jože Pirš ◽  
Marija Pavlin
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloys ◽  
Grain Boundaries ◽  
Aging Treatment ◽  
Mg Alloy ◽  
Age Hardening ◽  
Cu Alloy ◽  
Solute Depletion ◽  
Type Of Failure

In most age-hardening aluminum alloys, metallographic studies have shown that the extent of precipitation adjacent to grain boundaries is much less than that which occurs in the interior of the grains. The width of these almost precipitate-free regions, which are sometimes called denuded zones, and the extent of solute depletion with them are dependent upon the particular alloy and its aging treatment. It has been observed that these zones are relatively soft with the result that plastic deformation takes place preferentially within them. It has been shown 2-4 that there exists a tendency for intercrystalline cracking in fatigue when such zones are present. It is of interest to note that Broom et al. were able to reduce the incidence of this type of failure in an Al- 4 wt pct Cu alloy by stretching the material 10 pct prior to aging. This was later confirmed also on Al - 10 wt pct Mg alloy.

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