Characterization of the dissolution of the Al2Cu phase in two Al–Si–Cu–Mg casting alloys using calorimetry

Lasa, L.; Rodríguez-Ibabe, J.M.

doi:10.1016/s1044-5803(02)00283-8

Cited by 79 publications

(42 citation statements)

References 14 publications

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“…6Mg (wt-%) alloy (alloy B) heat treated for various times at 500uC as calculated both from reduction of DSC peak area and measured from image analysis of SEM images: amounts in as received condition were taken as 100% (from Ref. 48) performance of experiments can be deceptive: sample preparation and baseline instability can influence results. Also, identification of heat effects in the more complex alloys is not straightforward, and requires extensive supporting microstructural investigation.…”

Section: Discussionmentioning

confidence: 99%

“…According to the authors, the fractions of Al 2 Cu phase obtained from analysis of the incipient melting effect were 'in good agreement with metallographic measurements'. 48 However, a closer look at Fig. 31 shows that, especially for the thixoformed Al-15Si-4 .…”

Section: Volume Fractions Of Intermetallic Phases Measured From Solidmentioning

confidence: 93%

“…Lasa and Rodriguez-Ibabe 48 used this to study the homogenisation of two Al-Si-CuMg alloys with very similar compositions that were cast using different procedures. The DSC curves of a conventionally cast Al-12Si-4 .…”

Section: Solid State Reactionsmentioning

confidence: 99%

“…11). These endothermic effects were ascribed to the reaction 48 The total heat content was used as a measure of the amount of Al 2 Cu present after homogenisation, and thus the DSC data indicate that for the conventionally cast alloy at least 2 h were necessary to achieve the maximum amount of dissolution of Al 2 Cu and achieve equilibrium. The curves obtained for the thixoformed alloy show that the dissolution of Al 2 Cu was much faster in this alloy.…”

Section: Solid State Reactionsmentioning

confidence: 99%

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

Starink¹

2004

International Materials Reviews

287

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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Section: Discussionmentioning

confidence: 99%

Section: Volume Fractions Of Intermetallic Phases Measured From Solidmentioning

confidence: 93%

Section: Solid State Reactionsmentioning

confidence: 99%

Section: Solid State Reactionsmentioning

confidence: 99%

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

Starink¹

2004

International Materials Reviews

287

108

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“…Lasa and Rodriguez-Ibabe 48 found that below 10°C/min, a large amount of CuAl 2 was dissolved during heating. On the other hand, at higher heating rates (above 10°C/min), overlap of different eutectic reactions made it difficult to measure the peak energy accurately.…”

Section: Proposed Heat Treatments For Al-si-cu Alloysmentioning

confidence: 99%

Rôle d'addition de magnésium sur l'occurence de la fonte naissante dans les alliages expérimentaux et commerciaux Al-Si-Cu et son influence sur la microstructure et les propriétés de traction de l'alliage /

Yang¹

2006

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Aluminum-silicon (Al-Si) casting alloys are widely used in automotive applications on account of their high strength-to-weight ratio and ability to be cast into complex shapes. Among these alloys, 319 alloy, belonging to the Al-Si-Cu system is popularly employed in such applications, where magnesium is often added to the alloy for strengthening purposes. These alloys are usually heat treated in order to obtain an optimum combination of strength and ductility. The excellent castability and mechanical properties of such Al-Si-Cu-Mg alloys has made them commercially popular for industrial applications.The mechanical properties of a casting are controlled by its microstructure which, in turn, is influenced by the alloy composition and the solidification conditions employed. In the case of 319 type Al-Si-Cu-Mg alloys, this would involve the fineness of the primary aAl dendrites (as determined by the dendrite arm spacing (DAS) value), the Al-Si eutectic structure (i.e., an acicular vs. a fibrous Si morphology), the CuAl2 and other copper intermetallics, as well as other second phase constituents (Fe-intermetallics, Mg 2 Si, etc.), depending upon the alloying and trace elements present in the alloy. The normally acicular form of the eutectic Si can be transformed or 'modified' to the fibrous form by the addition of certain 'modifiers' such as Na or Sr to the alloy melt, to improve the alloy ductility and strength. Magnesium is also observed to modify the Si eutectic. However, as it also causes segregation of the copper phases, this can lead to problems related to the melting of the latter (termed 'incipient melting').The properties of alloys containing elements such as Cu and Mg can also be enhanced through heat treatment, where the formation of fine precipitates of C11AI2 and Mg2Si during aging result in the precipitation hardening of the alloy. A typical heat treatment consists of solution treatment and quenching, followed by artificial aging. Solution heat treatment is carried out to achieve maximum dissolution of the Cu and Mg into the aluminum matrix. For this purpose, the solution treatment temperature must be kept as close as possible to the Al-CuAb eutectic temperature, but, at the same time, limited to a safe level below the maximum to avoid incipient melting of the copper phases which would result in the formation of cavities after quenching and lower the alloy soundness.The solution heat treatment process can be carried out in either a single step or in multiple steps. Unfortunately, the single step or conventional solution heat treatment used for 319 alloys (-498 °C) is not capable of maximizing the dissolution of the Cu-rich phases, nor is it able to sufficiently modify the Si particle morphology, both of which are required for enhancing the alloy properties. To overcome this, a two-step solution treatment (conventional solution treatment followed by a higher temperature solution treatment) was suggested, that significantly improves the dissolution of the Cu-rich phase, giving rise to better homoge...

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Dissolution of Al₂Cu Precipitate in Al2024 Additively Manufactured by Electron Beam Melting

Kenevisi

Feng

2021

Adv Eng Mater

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Samples built by the additive manufacturing experience various thermal cycles during the process. This, as a result, defines the final microstructure of the samples. Herein, the dissolution of θ‐Al2Cu precipitate along the building direction during electron beam melting process is aimed at. Induced thermal cycles cause the layers to experience critical temperatures. The results show that the average fraction area of precipitates is decreased from 3.34% to 2.63% and finally to 2.02% by moving along the building direction from the top to the bottom. This is due to the fact that the first deposited layers are kept at temperatures more than 520 °C for longer times, which is higher than the critical temperature of Al2Cu dissolution. Because of the solubility limit of Cu in the matrix, precipitates are not fully dissolved. Comparing the ratio of the integration area of the strongest θ diffraction peak to that of the α matrix at different locations, the dissolution is also confirmed by X‐ray diffraction (XRD) results. The results of the tensile test also demonstrate a decline of about 29% in the mechanical performance by moving from the top to the bottom, which can be attributed to the precipitates’ dissolution and grain coarsening.

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Characterization of the dissolution of the Al2Cu phase in two Al–Si–Cu–Mg casting alloys using calorimetry

Cited by 79 publications

References 14 publications

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

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

Rôle d'addition de magnésium sur l'occurence de la fonte naissante dans les alliages expérimentaux et commerciaux Al-Si-Cu et son influence sur la microstructure et les propriétés de traction de l'alliage /

Dissolution of Al₂Cu Precipitate in Al2024 Additively Manufactured by Electron Beam Melting

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Characterization of the dissolution of the Al2Cu phase in two Al–Si–Cu–Mg casting alloys using calorimetry

Cited by 79 publications

References 14 publications

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

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

Rôle d'addition de magnésium sur l'occurence de la fonte naissante dans les alliages expérimentaux et commerciaux Al-Si-Cu et son influence sur la microstructure et les propriétés de traction de l'alliage /

Dissolution of Al2Cu Precipitate in Al2024 Additively Manufactured by Electron Beam Melting

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Dissolution of Al₂Cu Precipitate in Al2024 Additively Manufactured by Electron Beam Melting