DSC analysis of phase transformations during precipitation hardening in Al–Zn–Mg alloy (7020)

Chemingui, Mahmoud; Ameur, Rim; Optasanu, Virgil; Khitouni, Mohamed

doi:10.1007/s10973-018-7856-9

Cited by 29 publications

(7 citation statements)

References 43 publications

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“…When comparing the quenched state and ageing at 145 • C, we see that the position of the 3rd exothermic peak hardly changes, which indicates that the number density of the η' precipitates increase during artificial ageing. Similar descriptions of exothermic precipitation peaks and endothermic dissolution peaks are reported in the research [38][39][40][41].…”

Section: Resultssupporting

confidence: 82%

The Influence of Shot Peening and Artificially Ageing Aluminium Alloy 7075 on Corrosion Behaviour

et al. 2022

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This paper investigates the corrosion of shot peened AA7075 aluminium alloys aged at different temperatures. The surface integrity of the hardened layer was evaluated with SEM, EDS, differential scanning calorimetry, hardness, and roughness measurements, and in the end also with corrosion resistance tests. The research results indicated that there were significant differences in precipitates distribution between aluminium alloys artificially aged at different temperatures. As the ageing temperature increases, the microhardness decreases, which influences the final roughness condition of the surface layer after shot peening. The results of potentiodynamic polarisation tests indicate that shot peening enables shifting the pitting potential to positive values, which ensures slightly higher corrosion resistance. SEM images confirmed the dissolution of the aluminium matrix near the separated iron-rich phases of the Alx form (Fe, Mn) by the action of galvanic cells.

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Section: Resultssupporting

confidence: 82%

The Influence of Shot Peening and Artificially Ageing Aluminium Alloy 7075 on Corrosion Behaviour

et al. 2022

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“…Similarly to the situation of the first endothermic one, the location of the following exothermic peaks obtained for the ECAP-processed sample also shifted to somewhat lower temperatures at every heating rate. For instance, when applying the heating rate of 10 K/min, the exothermic peak of the un-deformed sample manifested with a maximum at 504 K and extended in the interval of 465-525 K. Meanwhile, in the case of the ECAP-processed sample, the corresponding peak appeared with a maximum at 484 K and extended over the temperature interval of 437-509 K. As the exothermic peak is ascribed to the formation of η phase particles and their coarsening [37,38], the present results clearly confirm the possibility of the ECAP process to induce the formation of the η and η precipitates. This is also demonstrated by the larger areas belonging to the peak under the DSC profile of the ECAP-processed sample, compared with that of the un-deformed sample (see Figure 4b).…”

Section: Specific Enthalpies Characterizing the Dissolution And Preci...mentioning

confidence: 98%

Effect of the Equal Channel Angular Pressing on the Microstructure and Phase Composition of a 7xxx Series Al-Zn-Mg-Zr Alloy

Ahmed,

Olasz,

Bobruk

et al. 2023

Materials

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A supersaturated Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by the equal-channel angular pressing (ECAP) technique at room temperature in order to obtain an ultrafine-grained (UFG) microstructure having an average grain size of about 260 nm. The hardness and microstructural characteristics, such as the phase composition and precipitations of this UFG microstructure were studied using depth-sensing indentation (DSI), transmission electron microscopy (TEM), as well as non-isothermal scanning of differential scanning calorimetry (DSC), and compared to the properties of the un-deformed sample. Emphasis was placed on the effect of the UFG microstructure on the subsequent thermal processes in DSC measurements. It has been shown that the ECAP process resulted in not only an ultrafine-grained but also a strongly precipitated microstructure, leading to a hardness (2115 MPa) two and a half times higher than the initial hardness of the freshly quenched sample. Because of the significant changes in microstructure, ECAP has also a strong effect on the dissolution (endothermic) and precipitation (exothermic) processes during DSC measurements, where the dissolution and precipitation processes were quantitatively characterized by using experimentally determined specific enthalpies, ΔH and activation energies, Q.

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“…Microscopy observation after annealing up to 360 °C proved presence of secondary Al3(Sc,Zr) particles in the AlZnMgCuScZr HR alloys [14]. Although secondary Al3(Sc,Zr) particles was not observed in the initial state of the AlZnMgCuScZr HR alloys, on the base of microhardness values and typical hardening effect of these particles (ΔHV ≈ 25-40 [13,17,21,22]) we assume their presence in the initial state of the AlZnMgCuScZr HR alloys, too. These particles probably precipitate during annealing at 300 °C/60 min before/during hot deformation.…”

Section: Resultsmentioning

confidence: 76%

THERMAL CHARACTERISTICS AND ELECTRICAL PROPERTIES OF HOT DEFORMED AA7075 ALLOYS WITH AND WITHOUT Sc, Zr ADDITIONS

Kodetová

Vlach

Leibner

et al. 2020

METAL 2020 Conference Proeedings

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In the present work AA7075 alloys with and without Sc, Zr addition after hot deformation were studied. Thermal responses of precipitation reactions of hot deformed alloys were studied by differential scanning calorimetry, the relative electrical resistivity changes were determined by DC four-point method. The interconnections of these two materials characteristics were presented. Thermal and electrical measurements were compared to microstructure development that was observed by scanning and transmission electron microscope. Two types of eutectic phase were proved at (sub)grain boundaries. In the AA7075-Sc,Zr alloy primary multilayer Al3(Sc,Zr) particles precipitated during casting and subsequent cooling. In the thermal curves one exothermic process at ~ 200 °C and the decrease of relative resistivity changes were observed. Apparent activation energy of this process was calculated using by Kissinger method as ~ 100 kJ/mol regardless Sc, Zr addition. Schematic timetemperature-transformation diagram of the exothermic process was done on the base of calorimetric measurements at different heating rates.

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DSC analysis of phase transformations during precipitation hardening in Al–Zn–Mg alloy (7020)

Cited by 29 publications

References 43 publications

The Influence of Shot Peening and Artificially Ageing Aluminium Alloy 7075 on Corrosion Behaviour

The Influence of Shot Peening and Artificially Ageing Aluminium Alloy 7075 on Corrosion Behaviour

Effect of the Equal Channel Angular Pressing on the Microstructure and Phase Composition of a 7xxx Series Al-Zn-Mg-Zr Alloy

THERMAL CHARACTERISTICS AND ELECTRICAL PROPERTIES OF HOT DEFORMED AA7075 ALLOYS WITH AND WITHOUT Sc, Zr ADDITIONS

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