Morphology and Crystallography of &amp;beta;-Mg&lt;SUB&gt;2&lt;/SUB&gt;Si Precipitation in Al-Mg-Si Alloys

Ohmori, Yasuya; Doan, Long Chau; Matsuura, Yutaka; Kobayashi, Sengo; Nakai, Kenta

doi:10.2320/matertrans.42.2576

Cited by 35 publications

(20 citation statements)

References 12 publications

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“…3). 24) The h D / h C ratio decreased drastically with increasing excess Si content above 0.2%. Thus the reaction D may be predominant in the low excess Si alloys.…”

Section: Dsc Resultsmentioning

confidence: 99%

“…Since the reaction D at a slow heating rate starts prior to the completion of the reaction C much faster than that at a rapid heating rate, the apparent peak C in slow heating will displace to lower temperatures, resulting in the low activation energy as expected from the Kissinger equation. 24) This may explain the low activation energy of this reaction.…”

Section: Discussionmentioning

confidence: 99%

“…3, h D / h C , would have increased with increasing excess Si content because the amounts of rodlike precipitates increase with increasing excess Si content as described in a previous paper. 24) However, h D / h C decreases drastically with increasing excess Si content above 0.2%. It should also be noted that cuboid β-Mg 2 Si particles precipitate densely in the excess Mg and the quasi-binary alloys aged to the temperature where the reaction D occurs as in Figs.…”

Section: Discussionmentioning

confidence: 99%

“…The diffraction pattern and its analysis indicate that the fine particles are of β-phase relating to the Al matrix with the cube-cube orientation relationship, i.e., (100) β (100) Al , (010) β (010) Al , as reported previously. 7,9,24) In the specimen aged to 635 K at 50 K/min, β needles disappeared almost completely and only cuboid β particles were recognised.…”

Section: Tem Observationsmentioning

confidence: 99%

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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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“…3). 24) The h D / h C ratio decreased drastically with increasing excess Si content above 0.2%. Thus the reaction D may be predominant in the low excess Si alloys.…”

Section: Dsc Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Tem Observationsmentioning

confidence: 99%

See 2 more Smart Citations

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

Ohmori¹,

Doan²,

Nakai³

2002

Mater. Trans.

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“…Several of these studies have been reported. [28][29][30][31][32] Recrystallisation is mostly evidenced by using high resolution scanning electron microscopy (SEM) in combination with electron backscatter diffraction (EBSD); crystallisation and devitrivication is best evidenced by X-ray diffraction; and nanocrystallisation is evidenced by TEM with SAD. Melting reactions can often be indirectly evidenced by studying eutectic structures in a sample that is rapidly solidified by quenching after having (partially) melted, using SEM (possibly in combination with EDS).…”

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confidence: 99%

Analysis of aluminium based alloys by calorimetry: quantitative analysis of reactions and reaction kinetics

Starink¹

2004

International Materials Reviews

286

108

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Differential scanning calorimetry (DSC) and isothermal calorimetry have been applied extensively to the analysis of light metals, especially Al based alloys. Isothermal calorimetry and differential scanning calorimetry are used for analysis of solid state reactions, such as precipitation, homogenisation, devitrivication and recrystallisation; and solid-liquid reactions, such as incipient melting and solidification, are studied by differential scanning calorimetry. In producing repeatable calorimetry data on Al alloys, sample preparation, reproducibility and baseline drift need to be considered in detail. Calorimetry can be used effectively to study the different solid state reactions and solid-liquid reactions that occur during the main processing steps of Al based alloys (solidification, homogenisation, precipitation). Also, devitrivication of amorphous and ultrafine grained Al based powders and flakes can be studied effectively. Quantitative analysis of the kinetics of reactions is assessed through reviewing the interrelation between activation energy analysis methods, equivalent time approaches, impingement parameter approaches, mean field models for precipitation, the Johnson-Mehl-Avrami-Kolmogorov model, as well as novel models which have not yet found application in calorimetry. Differential scanning calorimetry has occasionally been used in attempts to measure the volume fractions of phases present in Al based alloys, and attempts at determining volume fractions of intermetallic phases in commercial alloys and amounts of devitrified phase in glasses are reviewed. The requirements for the validity of these quantitative applications are also reviewed.Keywords: Differential scanning calorimetry, Precipitation, Aluminium, Modelling, Transformation IMR/419 IntroductionCalorimetry is an analysis technique that is part of a group of techniques collectively known as thermal analysis methods. In its broadest sense, thermal analysis refers to the measurement of changes in properties of substances under a controlled temperature program. Thermal analysis techniques can be classified according to the type of temperature program that the sample is subjected to and the measured (output) signal. The most commonly used temperature programs are either isothermal hold or heating (scanning) at constant rate, while more recently, temperature modulated scanning and reaction controlled heating have also found application. The signals measured in thermal analysis can include heat flows, temperature changes, mass, evolved gasses, length changes, elastic modulus, and many other properties that characterise properties or reactions of interest. Calorimetry refers to thermal analysis methods that measure the heat evolution from a sample under a controlled temperature program. The two most often applied calorimetry techniques are isothermal calorimetry and differential scanning calorimetry (DSC), which, as the name suggests, is by definition non-isothermal (i.e. a temperature scan). Apart from the more common applications to polymers,...

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Heat Treatment of Al–Mg–Si–Mn Alloys with Varying Mg/Si Ratio

Shah

Yoon

et al. 2022

The Minerals, Metals &Amp; Materials Series

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Morphology and Crystallography of β-Mg<SUB>2</SUB>Si Precipitation in Al-Mg-Si Alloys

Cited by 35 publications

References 12 publications

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

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

Analysis of aluminium based alloys by calorimetry: quantitative analysis of reactions and reaction kinetics

Heat Treatment of Al–Mg–Si–Mn Alloys with Varying Mg/Si Ratio

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