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Phase transformations in aluminium AlEr(Sc)-based alloys
Leibner, Michal ; Vlach, Martin (advisor) ; Minárik, Peter (referee)
The effects of Sc addition, different Er concentrations and deformation on phase transitions in Al(-Sc)-Er-Zr alloys were studied. Three distinct processes were identified during isochronal annealing in all of the alloys investigated. The first process with maximum at ~ 240 řC is probably related to clustering of Er or to clustering of Er and Sc atoms, respectively. This effect was more pronounced in the deformed alloy due to easier diffusion of solutes along dislocations and (sub)grain boundaries. The second process with a maximum around 360 řC stems from the formation of Al3Er or Al3(Er,Sc) particles, respectively. This effect was more pronounced and led to a more significant hardening in the Sc-containing alloy. The third process is most likely related to the formation of Zr-rich shell around the previously formed precipitates. After aging at 600 řC, precipitates with a core made of Al3Er phase and a shell made of Al3(Er,Zr) phase were observed in the Al-Er-Zr alloy.
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Influence of deformation on precipitation processes in commercial Al-based alloys with Sc,Zr-addition
Leibner, Michal ; Vlach, Martin (advisor) ; Cieslar, Miroslav (referee)
1 Abstract: Mechanical and thermal properties of Al-5.4wt.%Zn-3.1wt.%Mg-1.5wt.%Cu (AA- 7075), Al-5.2wt.%Zn-3.0wt.%Mg-1.4wt.%Cu-0.2wt.%Sc-0.1wt.%Zr (AA-7075-ScZr) and Al-2.93wt.%Mg-0.34wt.%Mn-0.33wt.%Si-0.22wt.%Fe-0.19wt.%Cr-0.24wt.%Sc-0.06wt.%Zr (AA-5754-ScZr) alloys in as-cast and cold-rolled states were studied by differential scanning calorimetry and microhardness measurements. The initial values of microhardness reflect an effect of cold-rolling. The Sc,Zr-addition caused a pronounced hardening during annealing above ~ 300 řC. An easier diffusion of Zn, Mg, Cu and Mn atoms along dislocations led to a precipitation of Zn,Mg,Cu-containing and Mn-containing particles at lower temperatures in comparison with the AA-7075(-ScZr) and AA-5754-ScZr alloy in the as-cast state, respectively. The Sc,Zr-addition does not significantly influence precipitation of the particles form the Al-Zn-Mg-Cu system.
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Influence of deformation on precipitation processes in commercial Al-based alloys with Sc,Zr-addition
Leibner, Michal ; Vlach, Martin (advisor) ; Cieslar, Miroslav (referee)
1 Abstract: Mechanical and thermal properties of Al-5.4wt.%Zn-3.1wt.%Mg-1.5wt.%Cu (AA- 7075), Al-5.2wt.%Zn-3.0wt.%Mg-1.4wt.%Cu-0.2wt.%Sc-0.1wt.%Zr (AA-7075-ScZr) and Al-2.93wt.%Mg-0.34wt.%Mn-0.33wt.%Si-0.22wt.%Fe-0.19wt.%Cr-0.24wt.%Sc-0.06wt.%Zr (AA-5754-ScZr) alloys in as-cast and cold-rolled states were studied by differential scanning calorimetry and microhardness measurements. The initial values of microhardness reflect an effect of cold-rolling. The Sc,Zr-addition caused a pronounced hardening during annealing above ~ 300 řC. An easier diffusion of Zn, Mg, Cu and Mn atoms along dislocations led to a precipitation of Zn,Mg,Cu-containing and Mn-containing particles at lower temperatures in comparison with the AA-7075(-ScZr) and AA-5754-ScZr alloy in the as-cast state, respectively. The Sc,Zr-addition does not significantly influence precipitation of the particles form the Al-Zn-Mg-Cu system.
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