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寿, 鈴木; 幹宏, 菅野; 吾朗, 伊藤

doi:10.2464/jilm.30.609

Cited by 23 publications

(12 citation statements)

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“…The subsequent migration of solute atoms to the prismatic dislocation loops will eliminate the loops, leading to the formation of solute atom clusters. These solute atom clusters are also difficult to observe by TEM as reported by Suzuki et al 32) In fact, according to our unpublished work, the isothermal ageing at 448 K for 10 min corresponds to the initial stage of β precipitation where such loops can never be observed. The exothermic heat and the activation energy for the reaction A are in the ranges from 1.9 to 3.8 J/g and 52.3 to 64.5 kJ/mol, respectively, as shown in Fig.…”

Section: Discussionmentioning

confidence: 87%

Ageing Processes in Al-Mg-Si Alloys during Continuous Heating

Ohmori¹,

Doan²,

Nakai³

2002

Mater. Trans.

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The precipitation behaviours during continuous heating in the Al-Mg 2 Si alloys with excess Mg and Si contents have been investigated by means of Vickers hardness measurements, differential scanning calorimetry and transmission electron microscopy. The first exothermic reaction occurring at the lowest temperatures is due to the annihilation of quenched-in vacancies by the collapse of vacancy clusters and the migration of vacancies to various sinks such as grain boundaries. The prismatic dislocation loops formed by this collapse are frequently observed. The second reaction detected as broad hardening increases with increasing excess Si content and can be interpreted as the formation of solute atom clusters. The sharp and large exothermic reaction inducing the largest hardening corresponds to the precipitation of β needles. The following exothermic reaction arises from the precipitation of β-Mg 2 Si particles. The formation of β and Type-B rods can be recognised in the quasi-binary and the excess Si at slightly higher temperatures.

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Section: Discussionmentioning

confidence: 87%

Ageing Processes in Al-Mg-Si Alloys during Continuous Heating

Ohmori¹,

Doan²,

Nakai³

2002

Mater. Trans.

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“…Therefore, it can be said that the influence of the natural aging on age hardening is extremely low. If under-aging at low temperature proceeds in the alloy system that hardens by the precipitation of Mg 2 Si phase, a negative effect in two-stage aging behavior 5,6) seems to appear in Al-10%Si-0.5%Mg alloy casting. In Al-Si-Mg system alloys, the influence of cooling rate during solidification, aging treatment condition and alloy composition on the positive and negative effects of two-step aging has to be examined in the near future.…”

Section: Age Hardeningmentioning

confidence: 99%

Evaluation of Age Hardening Behavior Using Composite Rule and Microstructure Observation in Al-Si-Mg Alloy Castings

et al. 2011

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Al-Si hypoeutectic alloys have excellent castability and sufficient strength in combination with other alloying elements. Especially, Al-Si alloy containing Mg used for high-quality die-casting is well-known as a high strength alloy brought by the appropriate heat treatment and consequential precipitation hardening of Mg 2 Si intermediate phase. T6-heat treatment must be applied for maximum strength, but solution at high temperature and quenching treatment often conduct the product deformation and extra cost for fabrication. Therefore only artificial aging (T5-heat treatment) at comparatively lower temperature is mainly applied to industrial die-casting products. However, there are few studies on age hardening characteristics supplied by T5-heat treatment to Al-Si hypoeutectic alloys. To understand the age hardening behavior of Al-10 mass%Si-0.5 mass%Mg and Al-10 mass%Si-0.8 mass%Mg alloys in detail, microstructure observation and hardness measurement were performed. These alloys quenched in iced water, naturally aged at room temperature and artificially aged at 423-523 K, showed conspicuously age hardening behavior. Age hardening of Al-Si-Mg alloy generally considered to be the main cause of the precipitation-based hardening in phase, nevertheless it was seen that precipitation occurred in -Al+Si eutectic phase. Consequently, from the microstructure observation using SEM, it's thought that the age hardening of these alloys was mainly composed of the hardness change in -Al+Si eutectic phase.

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“…Isoconcentration surface demonstrated the region of enriched solute atoms, including Mg and Si atoms, in the vicinity of the assumed dislocation lines. This indicated the formation of cluster (2), resulting in the preferential formation of cluster (2) The composition of cluster(2) was estimated to investigate the influence of the induced dislocations on the characteristics of cluster (2). Schematic illustration for the composition estimates technique are shown in Figure 5.…”

Section: Apt Characterization Of Nanoclusters In Cold Rolled Specimenmentioning

confidence: 99%

“…However, it has been recognized that precipitation of the strengthening β˝ phase is strongly affected by the heat-treatment history prior to the BH treatment [1]. Storage at room temperature (RT) before the BH treatment results in a low density of the β˝ phase, whereas pre-aging before RT storage can effectively eliminate the adverse effect of natural aging on the subsequent precipitate microstructures [2]. Pre-aging at ~373 K for times less than 30 min before RT storage has been applied in the manufacturing process in order to improve the BH response.…”

Section: Introductionmentioning

confidence: 99%

“…These two types of pre-precipitates were called nanoclusters, cluster(1) and cluster(2), because they were not considered to have the properties of a GP zone. Cluster(1) was the name given to the pre-precipitate formed at RT and cluster (2) for the one formed during the pre-ageing at 373 K. The presence of two types of nanoclusters has also been confirmed as two exothermic peaks by thermal analysis using differential scanning calorimetry (DSC) [4]. The DSC results also demonstrated that the two types of nanoclusters possess different thermal stabilities in that cluster(1) is stable at the BH temperature, whereas cluster(2) easily transforms into the β˝ phase.…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous Formation of Nanoclusters in a Cold Rolled 6000 Series Aluminum Alloy

Serizawa¹,

Hirai²,

Ishizaki³

2017

dtetr

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Abstract. The effect of high densities of dislocations on the formation behavior of nanoscale clusters (nanoclusters), which are formed during natural aging at room temperature and the pre-aging at ~373 K in a 6000 series aluminum alloy, was investigated by atom probe tomography. Cold rolling was applied to modify the formation behavior and/or the characteristics of the two types of nanoclusters and also the precipitation sequence, which involve a strengthening phase (β˝) to improve the bake-hardening (BH) response for auto body panels. Cold rolling to a 5% deformation accelerates the preferential formation of nanocluster at 373K along dislocations in addition to homogeneous nucleation in the crystal grains. Atom probe tomography demonstrate the heterogeneous formation of nanocluster during pre-aging at 373K. The β˝ phase shows the high growth rate at the same level of the as-quenched specimen in the cold rolled alloy on the aging curve at 443K. Cold rolling before pre-aging is an effective process to improve the BH response of the alloys.

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Abstract: Photo 4 Step-aged structures in specimens of 0.1mm thickness (pre-aging time, 15min). Rerfer to Fig. 7. Foil orientation, [001]. The figure shows that the structure is not homogeneous in this case.

Cited by 23 publications

References 1 publication

Ageing Processes in Al-Mg-Si Alloys during Continuous Heating

Ageing Processes in Al-Mg-Si Alloys during Continuous Heating

Evaluation of Age Hardening Behavior Using Composite Rule and Microstructure Observation in Al-Si-Mg Alloy Castings

Heterogeneous Formation of Nanoclusters in a Cold Rolled 6000 Series Aluminum Alloy

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