Technological aspects of friction stir processing of AlZn5.5MgCu aluminum alloy

FSP technology was used to modify the surface layer of the AlZn5.5.MgCu aluminum alloy by enriching its SiC particles. For this goal the FSP multi-chamber method was used. The SiC powder was placed in separated chambers hollowed in the modified material perpendicular to the surface of the sample. In order to achieve a more even distribution of the reinforcing phase in the aluminum alloy matrix and to minimize the risk of uncontrolled displacement of the SiC powder at the time of inserting the pin into the material, a two-step treatment was applied. In the first one, the working area of the pin was shifted relative to the axis of the chambers by ΔL. In the second step of the treatment the tool moved centrally along the line of chambers. As a result of friction treatment, intensive sputtering of SiC particles in the surface of the aluminum alloy and strong refinement of the alloy were observed. The consequence of the microstructural changes in the surface layer of the material and the formation of a metal-ceramic composite microstructure was a significant increase in the hardness of the aluminum alloy