Precipitation behaviors in Al-Cu-Mg and 2024 aluminum alloys

Shih, Han-Cheng; Ho, New-Jin; Huang, J.C.

doi:10.1007/bf02652342

Cited by 142 publications

(79 citation statements)

References 18 publications

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“…In addition, L1 2 ordered precursor structures to δ' can form, probably via congruent ordering or spinodal decomposition [17,18]. The second precipitation sequence involves Cu and Mg and, on the basis of X-ray diffraction (XRD) [19], atom probe field ion microscopy (APFIM) and transmission electron microscopy (TEM) evidence [20,21,22], is represented as:…”

Section: Precipitation In Al-li-cu-mg Alloysmentioning

confidence: 99%

“…interpreted in terms of disk shaped structures with radius of about 1 nm which were termed GPB zones [24], and mottled appearance of underaged Al-Cu-Mg alloys in conjunction with the appearance of diffraction rings in the selected area diffraction pattern has been related to GPB2 zones [22]. (Other, often conflicting, literature data on these zones and clusters has been reviewed in Ref.…”

Section: Precipitation In Al-li-cu-mg Alloysmentioning

confidence: 99%

“…(Other, often conflicting, literature data on these zones and clusters has been reviewed in Ref. [22].) However, no direct TEM observations of any of these zones have been reported.…”

Section: Precipitation In Al-li-cu-mg Alloysmentioning

confidence: 99%

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Microstrucure and strengthening of Al–Li–Cu–Mg alloys and MMCs: I. Analysis and Modelling of Microstructural changes

et al. 1999

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A complete and detailed analysis of the microstructural development during ageing in an 8090 (Al-2.3Li-1.2Cu-1Mg-0.1Zr) alloy, an 8090/20wt%SiC p MMC, an Al-1.5Li-Cu-Mg MMC and an Al-Cu-Mg MMC (all with similar Cu and Mg contents) has been performed. Volume fractions of all precipitates relevant for precipitation strengthening of the alloys (δ' phase, S' phase and GPB zones) have been determined using a recently derived method based on differential scanning calorimetry (DSC). The volume fractions have subsequently been successfully fitted using a novel model for transformation kinetics. The sizes of these precipitates have been analysed using newly derived expressions consistent with the latter model. As a result of dislocation generation around misfitting SiC particles the volume fractions of both GPB zones and S' phase depend strongly on the presence of these particles. Also the amount of Li present in the alloys influences the volume fractions of the phases significantly. The sizes of S' are similar for the four alloys. Introduction AimsMonolithic Al-based alloys for structural applications are generally strengthened by 4 basic mechanisms: precipitation strengthening, solution strengthening, grain and subgrain strengthening and strengthening by dislocations. The first two mechanisms depend strongly on composition of the alloy and on heat treatment and are generally employed in a metastable state, whilst the latter two mechanisms depend mostly on thermo-mechanical processing routes. In metal matrix composites (MMCs) additionally load transfer to ceramic inclusions in the matrix can increase the strength of the alloy (see e.g. [1,2]). Apart from this direct effect the presence of ceramic inclusions will also influence the precipitation in the matrix [1,3,4] and thus influence strengthening in an indirect way. The main aim of the present work and the companion paper [5] is to derive and validate a complete microstructure-property model for reinforced and unreinforced Al-Li-Cu-Mg type alloys and link this model with a novel model for the kinetics of microstructure development.

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Section: Precipitation In Al-li-cu-mg Alloysmentioning

confidence: 99%

Section: Precipitation In Al-li-cu-mg Alloysmentioning

confidence: 99%

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Microstrucure and strengthening of Al–Li–Cu–Mg alloys and MMCs: I. Analysis and Modelling of Microstructural changes

et al. 1999

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“…The structure of S"/GPB2 has not been clearly confirmed. Orthorhombic [1,[3][4][5], cubic [2], tetragonal [6,7] and monoclinic [8] structures have been proposed for the S"/GPB2 structure. S phase with composition of Al 2 CuMg has been determined as orthorhombic Cmcm structure with lattice parameters a S = 0.400 nm, b S = 0.923 nm, c S = 0.714 nm by Perlitz and Westgren [9] (PW) on the basis of X-ray diffraction (XRD) work.…”

Section: Introductionmentioning

confidence: 99%

Two types of S phase precipitates in Al–Cu–Mg alloys

2007

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Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) have been used to study S phase precipitation in an Al-4.2Cu-1.5Mg-0.6Mn-0.5Si (AA2024) and an Al-4.2Cu-1.5Mg-0.6Mn-0.08Si (AA2324) (wt.%) alloy. In DSC experiments on as solution treated samples two distinct exothermic peaks are observed in the range 250-350°C, whereas only one peak is observed in solution treated and subsequently stretched or cold worked samples. Samples heated to 270°C and 400°C at a rate of 10°C/min in the DSC have been studied by TEM. The selected area diffraction patterns show that S phase precipitates with the classic orientation relationship form during the lower temperature peak, and for the solution treated samples, the higher temperature peak is caused by the formation of a second type of S phase precipitates which have an orientation relationship that is rotated by ~4˚ to the classic one. The effects of Si and cold work on the formation of second type of S precipitates have been discussed.

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“…4.28 exhibited two exothermic peaks and two endothermic peaks. The first exothermic peak was attributed to the formation of GPB zones characteristic of Al-Cu-Mg alloys [24,25,26]. GPB2 may also form, perhaps in situ on GPB [24], during DSC runs although no separate exothermic peak was noted.…”

Section: Artificial Agingmentioning

confidence: 99%