Modelling differential scanning calorimetry curves of precipitation in Al–Cu–Mg

Hersent, Emmanuel; Driver, J.H.; Piot, David

doi:10.1016/j.scriptamat.2009.12.009

Cited by 23 publications

(11 citation statements)

References 9 publications

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“…That task might be solved by kinetic modelling. Some available models even allow the combination of both precipitation and dissolution to model the whole DSC heating curve from room temperature up to the solvus temperature (e.g., [ 30 , 31 , 32 , 33 , 34 ]).…”

Section: Resultsmentioning

confidence: 99%

Dissolution and Precipitation Behaviour during Continuous Heating of Al–Mg–Si Alloys in a Wide Range of Heating Rates

et al. 2015

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In the present study, the dissolution and precipitation behaviour of four different aluminium alloys (EN AW-6005A, EN AW-6082, EN AW-6016, and EN AW-6181) in four different initial heat treatment conditions (T4, T6, overaged, and soft annealed) was investigated during heating in a wide dynamic range. Differential scanning calorimetry (DSC) was used to record heating curves between 20 and 600 °C. Heating rates were studied from 0.01 K/s to 5 K/s. We paid particular attention to control baseline stability, generating flat baselines and allowing accurate quantitative evaluation of the resulting DSC curves. As the heating rate increases, the individual dissolution and precipitation reactions shift to higher temperatures. The reactions during heating are significantly superimposed and partially run simultaneously. In addition, precipitation and dissolution reactions are increasingly suppressed as the heating rate increases, whereby exothermic precipitation reactions are suppressed earlier than endothermic dissolution reactions. Integrating the heating curves allowed the enthalpy levels of the different initial microstructural conditions to be quantified. Referring to time–temperature–austenitisation diagrams for steels, continuous heating dissolution diagrams for aluminium alloys were constructed to summarise the results in graphical form. These diagrams may support process optimisation in heat treatment shops.

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Section: Resultsmentioning

confidence: 99%

Dissolution and Precipitation Behaviour during Continuous Heating of Al–Mg–Si Alloys in a Wide Range of Heating Rates

et al. 2015

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“…The uniform and fine grain size thus can be attributed to the occurrence of dynamic recovery, which leads to the formation of subgrain boundaries which progressively transform at large strains into new high angle grain boundaries. Furthermore, at this temperature (408ºC) based in DSC results [64] still dissolving alloying elements and incipient fine precipitates are present, which also contribute by a pinning effect, together with the high temperature, to this transformation of LABs into HABs.…”

Section: Discussionmentioning

confidence: 99%

Study of hot deformation of an Al–Cu–Mg alloy using processing maps and microstructural characterization

Cepeda-Jiménez¹,

Ruano²,

Carsí³

et al. 2012

Materials Science and Engineering: A

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The forming behaviour of an Al-Cu-Mg alloy (Al 2024-T351) has been studied by processing maps and microstructural characterization. Torsion tests were conducted in the range 278 to 467 ºC, between 2.1 and 25.6 s-1. Stress-strain curves obtained from the experiment data were fitted using the Garofalo equation to obtain the constitutive parameters, obtaining a stress exponent of 6.1 and an activation energy of 180 kJ/mol. Electron backscatter diffraction (EBSD) was employed to characterize the microtexture and microstructure, before and after torsion testing, to evaluate the microstructural changes and instability phenomena. A peak ductility of the Al 2024 alloy was found at about 400 ºC at all strain rates considered. According to the processing maps and microstructure observation, the optimum hot deformation condition for the Al 2024 alloy is in the range 360-410 ºC and 2.1-4.5 s −1. Under these favourable conditions a uniform and fine grain size is obtained by extended dynamic recovery (DRV), which leads to the formation of subgrain boundaries that progressively transform at large strains into new high angle grain boundaries.

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“…This leads to the need for developing new methods in the future for the evaluation of kinetic parameters, a problem which could be solved by kinetic modelling. Some available models even use a combination of both precipitation and dissolution to model the whole DSC heating curve from room temperature up to the solvus temperature (e.g., [152][153][154][155][156]). In the future, these models will need to implement the kinetic suppression of diffusion-controlled reactions.…”

Section: Capabilities and Limitations Of Dsc Heating Curve Analysis Amentioning

confidence: 99%

Review of the Quench Sensitivity of Aluminium Alloys: Analysis of the Kinetics and Nature of Quench-Induced Precipitation

et al. 2019

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For aluminium alloys, precipitation strengthening is controlled by age-hardening heat treatments, including solution treatment, quenching, and ageing. In terms of technological applications, quenching is considered a critical step, because detrimental quench-induced precipitation must be avoided to exploit the full age-hardening potential of the alloy. The alloy therefore needs to be quenched faster than a critical cooling rate, but slow enough to avoid undesired distortion and residual stresses. These contrary requirements for quenching can only be aligned based on detailed knowledge of the kinetics of quench-induced precipitation. Until the beginning of the 21st century, the kinetics of relevant solid-solid phase transformations in aluminium alloys could only be estimated by ex-situ testing of different properties. Over the past ten years, significant progress has been achieved in this field of materials science, enabled by the development of highly sensitive differential scanning calorimetry (DSC) techniques. This review presents a comprehensive report on the solid-solid phase transformation kinetics in Al alloys covering precipitation and dissolution reactions during heating from different initial states, dissolution during solution annealing and to a vast extent quench-induced precipitation during continuous cooling over a dynamic cooling rate range of ten orders of magnitude. The kinetic analyses are complemented by sophisticated micro- and nano-structural analyses and continuous cooling precipitation (CCP) diagrams are derived. The measurement of enthalpies released by quench-induced precipitation as a function of the cooling rate also enables predictions of the quench sensitivities of Al alloys using physically-based models. Various alloys are compared, and general aspects of quench-induced precipitation in Al alloys are derived.

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Modelling differential scanning calorimetry curves of precipitation in Al–Cu–Mg

Cited by 23 publications

References 9 publications

Dissolution and Precipitation Behaviour during Continuous Heating of Al–Mg–Si Alloys in a Wide Range of Heating Rates

Dissolution and Precipitation Behaviour during Continuous Heating of Al–Mg–Si Alloys in a Wide Range of Heating Rates

Study of hot deformation of an Al–Cu–Mg alloy using processing maps and microstructural characterization

Review of the Quench Sensitivity of Aluminium Alloys: Analysis of the Kinetics and Nature of Quench-Induced Precipitation

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