Effect of recrystallisation on Al3Zr dispersoid behaviour in thick plates of aluminium alloy AA7150

Zhang, Yong; Bettles, Colleen Joyce; Rometsch, Paul

doi:10.1007/s10853-013-7856-x

Cited by 46 publications

(24 citation statements)

References 19 publications

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“…Those reactions occur through a number of mechanisms, incl. precipitation on coarse intermetallics (phases that mostly are formed during solidification), precipitation on grain boundaries and precipitation in the grain, as well as, in particular for the lower temperature phases, precipitation on dispersoids (e. g. [7,8,25,30]). These reactions can occur consecutively or in overlapping time intervals.…”

Section: Microstructure Of Quenched Samplesmentioning

confidence: 99%

Quench sensitivity of Al–Mg–Si alloys: A model for linear cooling and strengthening

Milkereit

Starink

2015

Materials & Design

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This work studies the quench-induced precipitation during continuous cooling of five Al-Mg-Si alloys over a wide range of cooling rates of 0.05 -2•10 4 K/min using Differential Scanning Calorimetry (DSC), X-ray diffraction, optical-(OM), transmission electron-(TEM) and scanning electron microscopy (SEM) plus hardness testing. The DSC data shows that the cooling reactions are dominated by a high temperature reaction (typically 500 °C down to 380 °C) and a lower temperature reaction (380 °C down to 250 °C), and the microstructural analysis shows they are Mg2Si phase formation and B' phase precipitation, respectively. A new, physically-based model is designed to model the precipitation during the quenching as well as the strength after cooling and after subsequent age hardening. After fitting of parameters, the highly efficient model allows to predict accurately the measured quench sensitivity, the volume fractions of quench induced precipitates, enthalpy changes in the quenched sample and hardness values. Thereby the model can be used to optimise alloy and/or process design by exploiting the full age hardening potential of the alloys choosing the appropriate alloy composition and/ or cooling process. Moreover, the model can be implemented in FEM tools to predict the mechanical properties of complex parts after cooling.

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Section: Microstructure Of Quenched Samplesmentioning

confidence: 99%

Quench sensitivity of Al–Mg–Si alloys: A model for linear cooling and strengthening

Milkereit

Starink

2015

Materials & Design

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“…[3,23,[41][42][43][44][45]); and this reaction to a large extent determines the resulting mechanical properties of the material in quench conditions that are of industrial relevance. Hence we will pay special attention to this reaction.…”

Section: The Reactions During the Quenchmentioning

confidence: 99%

“…As there is no indication that the latter is a particularly strong effect, we will not consider this in the model. The mass density of MgZn2 is 5.09 g/cm 3 [51], which is equivalent to an atomic density that is virtually identical to that of the matrix, 20 and thus volume misfit strains on precipitation will be minimal. (For the metastable  phase the incorporation of Cu atoms is also considered to enhance phase stability [43,52,53].…”

Section: The Reactions During the Quenchmentioning

confidence: 99%

“…The latter particularly holds for incoherent dispersoids, whereby the dispersoids typically lose their coherence by recrystallization (e.g. [2,3]). Hence, also the degree of recrystallisation affects the quench sensitivity.…”

Section: Introductionmentioning

confidence: 99%

“…6). During cooling/quenching the Mg(Zn,Al,Cu)2 precipitates nucleate preferentially on defects such as dislocations, grain boundaries and free surfaces that can reduce the activation energy barrier including dispersoids-matrix interfaces that are incoherent [3,23]. Fig.…”

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Predicting the quench sensitivity of Al–Zn–Mg–Cu alloys: A model for linear cooling and strengthening

et al. 2015

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In this work the quench sensitivity of Al-Zn-Mg-Cu alloys is studied through continuous cooling at constant rates of a range of alloys using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and hardness testing. The DSC, TEM and SEM data show that the cooling reactions are dominated by a high temperature reaction (typically ~450 °C down to ~350 °C) due mostly to S-Al2CuMg phase formation, a medium temperature reaction (~350 °C down to ~250 °C) due predominantly to -Mg(Al,Cu,Zn)2 phase formation and a lower temperature reaction (~250 °C down to ~150 °C) due to a Zn-Cu rich thin plate phase. A new, physically-based model is constructed to predict rates of all reactions, enthalpy changes and resulting yield strength in the artificially aged condition. The model incorporates a recently derived model for diffusion-controlled reactions based on the extended volume fraction concept as well as recent findings from first principles modelling of enthalpies of the relevant phases. The model shows a near perfect correspondence with data on all 6 alloys studied extensively by cooling DSC and hardness testing, and 2 allows prediction of the influence of the 3 major elements and 3 dispersoid forming elements on quench sensitivity. Graphical abstract Highlights

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On the extraordinary low quench sensitivity of an AlZnMg alloy

et al. 2021

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The scope of this work was to investigate the quench sensitivity of a high-purity wrought aluminum alloy Al6Zn0.75 Mg (in this work called 7003pure). This is compared to a similar alloy with the additions of Fe, Si, and Zr at a sum less than 0.3 at.% (in this work called 7003Fe,Si,Zr). Differential scanning calorimetry (DSC) was used for an in situ analysis of quench induced precipitation in a wide range of cooling rates varying between 0.0003 and 3 K/s. In 7003pure, three main precipitation reactions were observed during cooling, a medium temperature reaction with a distinct double peak between 325 and 175 °C and a very low temperature reaction starting at about 100 °C. An additional high temperature reaction related to the precipitation of Mg2Si starting at 425 °C has been observed for 7003Fe,Si,Zr. In terms of hardness after natural as well as artificial aging, alloy 7003pure shows a very low quench sensitivity. Hardness values on the saturation level of about 120 HV1 are seen down to cooling rates of 0.003 K/s. The as-quenched hardness (5 min of natural aging) shows a maximum at a cooling rate of 0.003 K/s, while slower and faster cooling results in a lower hardness. In terms of hardness after aging, 0.003 K/s could be defined as the technological critical cooling rate, which is much higher for 7003Fe,Si,Zr (0.3–1 K/s). The physical critical cooling rates for the suppression of any precipitation during cooling were found to be about 10 K/s for both variants.

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Effect of recrystallisation on Al3Zr dispersoid behaviour in thick plates of aluminium alloy AA7150

Cited by 46 publications

References 19 publications

Quench sensitivity of Al–Mg–Si alloys: A model for linear cooling and strengthening

Quench sensitivity of Al–Mg–Si alloys: A model for linear cooling and strengthening

Predicting the quench sensitivity of Al–Zn–Mg–Cu alloys: A model for linear cooling and strengthening

On the extraordinary low quench sensitivity of an AlZnMg alloy

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