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Joining procedure for aluminum alloy 7075–T6 (AlZnMgCu1.5) sheets was realized by Impulse Friction Stir Welding (IFSW) with different impulse frequencies. The additional mechanical impulses during IFSW enhance the forging action of the tool, resulting in the weld microstructure modification. The microstructural evolution in different zones of the weld was studied, focusing on the strengthening precipitation behavior of the welded joint as well as the overall mechanical properties. The results illustrate that the application of impulses during IFSW accelerates the reprecipitation and dynamic recrystallization processes, which lead to the formation of strengthening precipitates and the homogeneous grain microstructure, respectively, in the SZ. HAZ of the welds obtained by the FSW and IFSW represent dislocation free grains interior. The precipitation content in the HAZ of the welds obtained by conventional FSW and IFSW is completely different. The HAZ of the weld obtained by conventional FSW represent high concentration of stable η phase. Conversely, high concentrations of heat sensitive phase - η' precipitates - were found in the HAZ microstructure of the joints obtained by IFSW.

Joining procedure for aluminum alloy 7075-T6 (AlZnMgCu1.5) sheets was realized by Impulse Friction Stir Welding (IFSW) with different impulse frequencies. The additional mechanical impulses during IFSW enhance the forging action of the tool, resulting in the weld microstructure modi cation. The microstructural evolution in different zones of the weld was studied, focusing on the strengthening precipitation behavior of the welded joint as well as the overall mechanical properties. The results illustrate that the application of impulses during IFSW accelerates the reprecipitation and dynamic recrystallization processes, which lead to the formation of strengthening precipitates and the homogeneous grain microstructure, respectively, in the SZ. HAZ of the welds obtained by the FSW and IFSW represent dislocation free grains interior. The precipitation content in the HAZ of the welds obtained by conventional FSW and IFSW is completely different. The HAZ of the weld obtained by conventional FSW represent high concentration of stable η phase. Conversely, high concentrations of heat sensitive phase -η' precipitates -were found in the HAZ microstructure of the joints obtained by IFSW.

Nanostructured Fe–ZrO2 composite powders with homogeneous distribution of zirconia were synthesized by thermochemical process. The synthesis procedures are (1) preparation of precursor powder by spray-drying of solution made from water-soluble iron and zirconium nitrates, (2) air heat treatments to evaporate volatile components in the precursor powder and synthesis of nanostructured Fe2O3 +ZrO2, and (3) Fe2O3 reduction by hydrogen into pure Fe. In order to find phase containing Zr the powder was treated with 15% hydrochloric acid to dissolve iron particles. The size of the particles is less than 50 nm. Fe–ZrO2 composite powders can be used as filler for cored welding wire. Shown that particles zirconium oxide well affect the final structure of the weld.

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