Mechanical properties and structure formation of aluminum-silicon alloys after friction stir processing

This study presents the results of experimental work on obtaining and investigating samples obtained by multipass friction stir processing of the Al-12 %Si and Al-9 %Si aluminum-silicon alloys. The results indicate a beneficial effect of friction stir processing on the strength properties of both alloys. The number of tool passes along the processing line has no effect on the mechanical properties and particle size of silicon in the aluminum matrix. The greatest influence on the mechanical properties is exerted by the first pass with the tool. The yield strength of the processed Al-9 %Si alloy increases by more than a factor of 1.5, whereas for the Al-12 %Si alloy there is no increase in yield strength. The tensile strength of the Al-12 %Si alloy increases by 17 %, while that of the Al-9 %Si alloy increases by 29 %. The most significant is the increase in relative elongation to failure, namely 77 % for Al-12 %Si and 113 % for Al-9 %Si.