TY - JOUR N2 - The article presents the investigations of 7xxx aluminium alloys performed by the method of thermal and derivational analysis. The studies made it possible to identify the effect of the changes in the Cu concentration, the total Zn and Mg weight concentrations and the Zn/Mg weight concentration ratio on their crystallization process: the cooling as well as the kinetics and dynamics of the thermal process of cooling and crystallization. Metallographic studies were performed on the microstructure of the examined alloys and their HB hardness was measured. The evaluation of the changes was presented in reference to the model alloys EN AW-7003 and EN AW-7010, whose microstructure under the conditions of thermodynamic equilibrium are described by the phase diagrams: Al-Zn-Mg and Al-Zn-Mg-Cu. The performed investigations confirmed that the hardness HB of the examined alloys is mainly determined by the reinforcement of the matrix αAl by the introduced alloy additions and the presence of phases Θ(Al2Cu) and S(Al2CuMg) rich in copper, as well as η(MgZn2), in the examined alloys' microstructure. The increase of the amount of intermetallic phases precipitated in the microstructure of the examined alloys is caused, beside Cu, by the characteristic change of Zn wt. concentration and Mg. It was proposed that the process of one-stage thermal treatment of the examined alloys be introduced at a temperature of up to tJ-20 °C, which will prevent the exceedance of the solidus temperature. L1 - http://www.journals.pan.pl/Content/107843/PDF/AFE%204_2018_08.pdf L2 - http://www.journals.pan.pl/Content/107843 PY - 2018 IS - No 4 EP - 44 KW - Innovative casting materials and technologies KW - Al-Zn-Mg-Cu alloys KW - TDA method KW - microstructure KW - Hardness HB A1 - Pisarek, B.P. A1 - Czekaj, E. A1 - Pacyniak, T. PB - The Katowice Branch of the Polish Academy of Sciences VL - vol.18 DA - 2018.10.24 T1 - Study of the Influence of Additions on the Formation of Microstructure of Al-Zn-Mg-Cu Alloys SP - 39 UR - http://www.journals.pan.pl/dlibra/publication/edition/107843 T2 - Archives of Foundry Engineering ER -