One of methods of obtaining a fine globular microstructure in a semi‐solid range, necessary for thixoforming process, is modifiers additions. For this purpose 0.5 weight percent of modifying elements–scandium and zirconium–was added to 7075 alloy. The microstructure of such alloy consisted of homogeneously distributed globular grains of solid solution with the following chemical composition: Mg – 1.9%, Al – 91.6%, Cu – 1.0%, Zn – 5.5% (all in wt.%). Quantitative metallographic analysis showed that the average grain size was 23.5 μm, much smaller than in the alloy without additions and 3.08% volume fraction of precipitates in the form of a layer between spherical α(Al) grains. X‐ray phase analysis of the 7075 alloy with Sc and Zr additions confirmed the dominant presence of aluminum solid solution and the intermetallic hexagonal phase MgZn2. Electron diffraction pattern confirmed location of η MgZn2 phase at the grain boundaries. EDS chemical analysis of the η MgZn2 phase showed following content of elements: Mg – 17.2%, Al – 20.4%, Cu – 27.8%, Zn – 34.6%. The larger amount of Cu and Al indicated non‐stoichiometry of the η phase, which can be presented with a formula [Mg(Zn,Al,Cu)2]. Additionally, inside the aluminum solution, small, square‐shaped precipitations enriched with Sc and Zr were observed. Electron diffraction pattern allowed identification of the precipitates as cubic Al3(Sc,Zr) phase. The average hardness of feedstock was 105 HV5. DSC analysis during heating of the alloy enabled the estimation of a solidus line, at temperature of 548° C and a liquidus line at temperature: 656° C. For cooling, the temperatures for solidus and liquidus were 545° C and 636° C respectively. Additionally, the relation of liquid phase as a function of temperature was determined. Measurements of rheological properties in the semi‐solid range, using the Searl system indicated that an increase of a particle size leads to an observable decrease of viscosity during isothermal shearing.

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