Abstract
In the present work hot rolled AlZnMgCu alloys with and without Sc,Zr addition were studied. First, the temperature and time of annealing of hot rolling was looking for.
Then, precipitation reactions of hot rolled alloys were studied by differential scanning calorimetry and microhardness measurements during annealing from room temperature up to 450 °C. These measurements were compared to microstructure development that was observed by scanning electron microscope and by electron backscattered diffraction.
The grain size was ~ 20 microm in the AlZnMgCuScZr and ~ 1000 microm in the AlZnMgCu alloy. Microstructure observation proved eutectic phase at (sub)grain boundaries.
Primary multilayer Al3(Sc,Zr) particles also precipitated during casting and subsequent cooling in the alloy with Sc,Zr addition. These particles were observed in the alloy with Sc,Zr addition after annealing up to 450 °C, too.
In the DSC curves the exothermic process at ~ 200 °C was observed. Activation energy of the process was calculated.
There were observed constant values of microhardness (in accuracy of measurements) during annealing up to 450 °C. Higher microhardness values were measured in the alloy with Sc,Zr addition.