Precipitation Behaviour of AI-Mg-Si Ternary Alloys

Takeda, M.; Ohkubo, F; Shirai, T; Fukui, Kouichiro

doi:10.4028/www.scientific.net/msf.217-222.815

Cited by 15 publications

(16 citation statements)

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“…These precipitates are regarded as the b¢¢ phase, as previously reported for needlelike precipitates in Al-MgSi alloys. [2][3][4][5]9,11] In contrast, a much smaller amount of the b¢¢ phase is observed in the two-step-aged specimen when Cluster(1) was formed during natural aging ( Figure 6(b)). This result suggests that the formation of the b¢¢ phase during the BH treatment is suppressed in the two-step-aged specimen, compared to the directaged specimen.…”

Section: A Nanoscale Microstructures Before Bh Treatmentmentioning

confidence: 53%

“…Recently, an adiabatic calorimetry analysis of Al-1.4 pct Mg 2 Si and Al-1.4 pct Mg 2 Si-0.3 pct Si alloys by Yamada et al found that two types of pre-precipitates are formed, i.e., one at a temperature between 273 and 343 K and another at temperatures higher than 343 K. [6,7] It is worth noting that these findings have not been observed by other thermal analyses, [2,3,[8][9][10][11][12] because the majority of these studies do not scan below RT. The present authors conducted the differential scanning calorimetry (DSC) analysis in order to confirm the presence of two types of nanoclusters by measuring from 223 K. It is demonstrated that the two types of nanoclusters are present and that their thermal stabilities are different from each other.…”

Section: Introductionmentioning

confidence: 98%

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Three-Dimensional Atom Probe Characterization of Nanoclusters Responsible for Multistep Aging Behavior of an Al-Mg-Si Alloy

Serizawa

Hirosawa

Sato

2008

Metall Mater Trans A

265

146

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The characterization of nanoscale clusters (nanoclusters) was performed using differential scanning calorimetry (DSC) and a three-dimensional atom probe (3DAP), to clarify the complicated aging behavior of an Al-Mg-Si alloy. The DSC results conducted over the temperature range 223 to 473 K revealed that two types of nanoclusters, i.e., Cluster(1) and Cluster(2), were formed near room temperature (RT) and 373 K, respectively. In the present work, the quantitative estimation of atom maps of the 3DAP analysis revealed the difference in the growth mechanism and the composition distribution of the two types of nanoclusters. The distribution of both the size and Mg/Si ratio of Cluster(1) does not change during prolonged natural aging. On the other hand, Cluster(2) grows gradually with preaging time. The Mg/Si ratio of the larger-sized Cluster(2) approaches a constant value that is equal to that of the b¢¢ phase. The difference in the two-step aging behavior can be explained by the different growth mechanisms and chemical compositions of the two nanoclusters. This means that only Cluster(2) can easily transform continuously into the b¢¢ phase during the BH treatment, due to its size and compositional similarity.

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Section: A Nanoscale Microstructures Before Bh Treatmentmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 98%

Three-Dimensional Atom Probe Characterization of Nanoclusters Responsible for Multistep Aging Behavior of an Al-Mg-Si Alloy

Serizawa

Hirosawa

Sato

2008

Metall Mater Trans A

265

146

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“…The curve of the solution-treated alloy in Figure 4(a) agrees well with DSC traces of similar 6XXX series alloys with excess Si. [11,20,22,23] The broad exothermic peak at 130 °C to 150 °C, often interpreted as two partially superimposed subpeaks, corresponds to the formation of ␤Љ and ␤Ј metastable precipitates. More specifically, the subpeak at 130 °C could also be related to the precipitation of tiny Si-rich particles acting as precursors for the formation of ␤Љ phase, and at 150 °C, both lath shaped ␤Ј precipitates and relatively large Si precipitates are present.…”

Section: Figures 1(a) and (B)mentioning

confidence: 99%

“…Other hardening particles found in the 6082 alloy correspond to the rounded Si phase. [1][2][3]9,14,22,23] More complex intermetallics may also be present in the form of quaternary Al-Fe-Mn-Si phases, whose elements may have slightly different stoichiometric relationships. [11,20] In recent decades, the need to improve the mechanical properties of light alloys has oriented industry's attention and the research efforts toward two different, but parallel, fields.…”

Section: Introductionmentioning

confidence: 99%

Influence of severe plastic deformations on secondary phase precipitation in a 6082 Al-Mg-Si alloy

Cabibbo

Evangelìsta

Vedani

2005

Metall Mater Trans A

105

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The role of severe plastic deformation on the second-phase stability in a 6082 Al-Mg-Si alloy was studied using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) techniques. The alloy was fully annealed prior to undergoing up to six equal channel angular pressing (ECAP) passes using route C. The Orowan strengthening mechanism was calculated on the basis of TEM inspections for the two hardening second-phase precipitates: Mg 2 Si and Si. The former had a major tendency to be cut and fragmented by dislocations, while in the latter, a dissolution process was induced by severe plastic deformation. Accordingly, the second-phase Si particles became progressively less effective with increasing deformation (i.e., additional ECAP passes). The increase in hardness with the ECAP passes was mostly due to the grain refining mechanism and to dislocation tangles within the newly formed grains. The expected, though if limited, contribution of second-phase hardening was prevalently accounted for by the Mg 2 Si particles.

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“…1, the DSC spectra of the ␤(1) and ␤(2) specimens are shown for both alloys. The ␤(1) spectrum displays a ␤ dissolution peak (Ref 16,(21)(22)(23) at 746 K (AA6063) or 763 K (AA6005). The difference in peak temperatures is due to the difference in solvus temperature, and the difference in peak area is due to the difference in Mg and Si content.…”

Section: Evaluation Of Initial Microstructurementioning

confidence: 99%

Modification of a Thermomechanical Model to Predict Constitutive Behavior of Al-Mg-Si Alloys

Langkruis

Kool

Zwaag

2006

Journal of Materials Engineering and Performance

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A previously developed constitutive model for quantification of the effect of the condition of Mg and Si in AA6xxx alloys was used for the prediction of the flow stresses measured by plane strain compression (PSC) tests. As an extension of earlier work, two AA6xxx alloys were subjected to different thermal pretreatments and were plane strain compression tested at temperatures and strain rates typical for hot extrusion. Heating rates to the test temperature were varied. Dissolution behavior of the ␤ precipitates, needed for the quantification, was experimentally validated using differential scanning calorimetry. Significant differences in flow stress during PSC testing were observed as a function of the heating rate to the deformation temperature and of the different conditions that resulted from the different thermal pretreatments. The model was also applied to the combined set of present data and data reported earlier. This combined set of data encompasses a wide range of alloy compositions and thermal histories. It is found that the model gives a fair prediction. Excellent agreement was obtained by assuming that the parameter describing the solution hardening behavior in the model is temperature dependent instead of constant.

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Precipitation Behaviour of AI-Mg-Si Ternary Alloys

Cited by 15 publications

References 0 publications

Three-Dimensional Atom Probe Characterization of Nanoclusters Responsible for Multistep Aging Behavior of an Al-Mg-Si Alloy

Three-Dimensional Atom Probe Characterization of Nanoclusters Responsible for Multistep Aging Behavior of an Al-Mg-Si Alloy

Influence of severe plastic deformations on secondary phase precipitation in a 6082 Al-Mg-Si alloy

Modification of a Thermomechanical Model to Predict Constitutive Behavior of Al-Mg-Si Alloys

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