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The article presents an assessment of the possibility of using ashes from the combustion of coal and biomass as a reinforcing phase in metal matrix composites. The composite surface layer was produced by means of the FSP (friction stir processing) method, using an original hole solution with a shifted working zone of the pin. The composite matrix was AA7075 alloy. The obtained composite was subjected to microscopic observations, tribological tests, and hardness measurements. The microscopic examinations revealed favorable changes in the microstructure, in particular, strong refinement of the grains, uniform distribution of the reinforcing phase, and good bonding of the particles of this phase with the matrix material. Changes in the microstructure resulted in a significant increase in the hardness (from 36 to 41% depending on the type of reinforcing phase) and wear resistance (from 24.1 to 32.9%), despite partial dissolution of the intermetallic phases. It was found that the effect of strengthening the matrix and the uniformity of the distribution of the reinforcing phase depend on the physicochemical properties of the used powders, especially on the shape and size of the particles. The research shows that the use of ashes as a reinforcing phase in composites is fully justified.

7075 aluminum alloy in the T6 state was subjected to surface remelting treatment using Gas Tungsten Arc Welding (GTAW). The changes in the material microstructure were examined by means of light microscopy, scanning electron microscopy and EDS. Moreover, profilometric tests and comparative measurements of material hardness in the state before and after the treatment were conducted. In the remelted layer strong microstructure refinement and the disappearance of microstructure banding were found. A fine dendritic microstructure was dominant in the remelted zone. Use of the GTAW method reduced the number of intermetallic precipitates in the surface layer. A consequence of dissolving the precipitates was a decrease in the hardness of the material in relation to the hardness before the modification. All the samples were characterized by the presence of a remelted zone, a narrow partially remelted zone and a wide heat affected zone. With an increase in the heat source travel speed, and consequently less heat entering the remelted material, the dimensions of the individual zones decreased. The conducted research showed that GTAW technology can be used in the surface remelting treatment of aluminum alloys and can be a competitive solution in comparison to other technologies.