Cluster formation and two-step aging behaviors of Al-Mg-Si alloys.

健太郎, 山田; 達雄, 里; 彰彦, 神尾

doi:10.2464/jilm.51.215

Cited by 45 publications

(20 citation statements)

References 14 publications

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“…That is why the characterization of the nanoclusters is preferentially required. Yamada et al 11) and Serizawa et al 12) clearly revealed the existence of the two types of nanoclusters, Cluster (1) and Cluster (2) formed at around room temperature and 100°C in Al-Mg-Si alloys, respectively.…”

Section: Introductionmentioning

confidence: 99%

Influence of Natural Aging Time on Two-Step Aging Behavior of Al-Mg-Si(-Cu) Alloys

2015

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Nanoclusters formed during natural aging cause the negative effect of the two-step aging in the age-hardenable Al-Mg-Si alloys. The relationship between the clustering behavior during natural aging and the two-step aging behavior was studied using the hardness, differential scanning calorimetry (DSC), electrical resistivity measurements, transmission electron microscopy (TEM) observation in the Cu-free and Cuadded Al-Mg-Si alloys. Three stages during the two-step aging are clearly revealed based on the hardness results. The hardness in the two-step aging with the natural aging time is decreased, increased and then decreased at the initial, middle and final stages, respectively. Si-rich clusters initially formed during natural aging do not transform into the ¢AA phase and are thermally stable during the two-step aging at 170°C. On the other hand, Mg-Si co-clusters formed at the middle stage during natural aging transform into the ¢AA phase and are thermally unstable during the twostep aging at 170°C. Much higher hardness is obtained in the Cu-added alloy than that of the Cu-free alloy during two-step aging when natural aging is performed for 3.6 ks belonging to the initial stage. The higher hardness is also found to be obtained during over-aging regardless of the natural aging time in the Cu-added alloy than that of the Cu-free alloy. The relationship between the clustering behavior during natural aging and the two-step aging behavior is discussed based on the observed age-hardening phenomena.

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Section: Introductionmentioning

confidence: 99%

Influence of Natural Aging Time on Two-Step Aging Behavior of Al-Mg-Si(-Cu) Alloys

2015

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“…The direct observation of the nanoscale clusters using the atom probe technique 911) provides the chemical composition and size distribution of nanoclusters in AlMgSi alloys. Yamada et al 12) and Serizawa et al 11,1315) found two types of nanoclusters and well explained the characteristics of nanoclusters such as the formation temperature, growth mechanism and interaction with dislocations in AlMgSi alloys. With those phenomena, understanding of the clustering behavior has become extremely attractive since nanoclusters formed during low temperature aging strongly affect the two-step aging or multistep aging behavior in AlMgSi alloys.…”

Section: Introductionmentioning

confidence: 81%

Thermal Stability and Transition Behavior of Nanoclusters during Two-Step Aging at 250°C in Al–Mg–Si(–Cu) Alloys

Kim

Kobayashi

et al. 2014

Mater. Trans.

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Two types of nanoclusters, Cluster (1) and Cluster (2), play an important role in the age-hardening behavior in AlMgSi alloys. Both Cluster (1) formed during natural aging at room temperature and Cluster (2) formed during pre-aging at 100°C cause the higher hardness and higher number density of the ¢″ phase during the two-step aging at 250°C than those of the single-aged specimen. Both of Cluster (1) and Cluster (2) result in the positive effect of two-step aging even though the mechanism is different. The positive effect of two-step aging for the naturally-aged specimen is caused by the atomic rearrangement from Cluster (1) to the Pre-¢″ phase at the early stage of aging at 250°C. On the other hand, Cluster (2) is stable up to 250°C and directly transforms into the ¢″ phase. The thermal stability of nanoclusters and their transition behavior are discussed based on the age-hardening phenomena.

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“…9(a). 20) With increasing aging time at RT (pre-aging), the peak hardness increases larger than that of the directly aged specimen. Two-step aging causes a positive effect.…”

Section: The Two-step Aging Behavior Of Other Commercialmentioning

confidence: 99%

Effects of the Pre-Aging Period on the Formation Behavior of Nanoclusters in an Al-Mg-Cu Alloy

2015

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The effects of the pre-aging period on the formation behavior of nanoclusters during two-step aging in an Al-3.0Mg-1.0Cu (mass%) alloy has been investigated by the hardness, differential scanning calorimetry (DSC) and electrical resistivity measurement. Two-step aging which consists of pre-aging and final aging results in an increase of the peak hardness. When the pre-aging is conducted at 323 K for 1.2 ks, the hardness dramatically increases after the final aging treatment. This pre-aging period corresponds to the incubation stage which is one of the hardening stages in an Al-Mg-Cu alloy. During the pre-aging, no clear hardness and electrical resistivity increase are obtained, however a certain structural change is considered to occur. In this study, co-clusters are assumed to be formed during pre-aging. On the contrary, when the preaging period is 345.6 ks, the hardness and electrical resistivity decrease in the beginning of final aging. It is attributed to the reversion of nanoclusters. In this case, the pre-aging period corresponds to the first stage of hardening. The first stage of hardening, which occurs rapidly (e.g. within 60 s at 443 K) and contributes 60% of the total hardening, is attributed to solute clustering rather than to the formation of GPB zones.

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Cluster formation and two-step aging behaviors of Al-Mg-Si alloys.

Cited by 45 publications

References 14 publications

Influence of Natural Aging Time on Two-Step Aging Behavior of Al-Mg-Si(-Cu) Alloys

Influence of Natural Aging Time on Two-Step Aging Behavior of Al-Mg-Si(-Cu) Alloys

Thermal Stability and Transition Behavior of Nanoclusters during Two-Step Aging at 250°C in Al–Mg–Si(–Cu) Alloys

Effects of the Pre-Aging Period on the Formation Behavior of Nanoclusters in an Al-Mg-Cu Alloy

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Cluster formation and two-step aging behaviors of Al-Mg-Si alloys.

Cited by 45 publications

References 14 publications

Influence of Natural Aging Time on Two-Step Aging Behavior of Al-Mg-Si(-Cu) Alloys

Influence of Natural Aging Time on Two-Step Aging Behavior of Al-Mg-Si(-Cu) Alloys

Thermal Stability and Transition Behavior of Nanoclusters during Two-Step Aging at 250&deg;C in Al&ndash;Mg&ndash;Si(&ndash;Cu) Alloys

Effects of the Pre-Aging Period on the Formation Behavior of Nanoclusters in an Al-Mg-Cu Alloy

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Thermal Stability and Transition Behavior of Nanoclusters during Two-Step Aging at 250°C in Al–Mg–Si(–Cu) Alloys