DANIELA MONICA IORDACHE, EDUARD LAURENTIU NITU, ADRIANA GABRIELA PLAIASU, LIA NICOLETA BOTILA, MARIAN CATALIN DUCU, MARIA MINODORA PASARE ANALYSIS OF MICROSTRUCTURE AND MECHANICAL PROPERTIES OF FSW OVERLAY JOINTS FOR DISSIMILAR MATERIALS Welding of Al and Cu materials by friction with active rotating element is of particular interest, being used in various branches of industry due to superior properties. The paper is centred on the analysis of microstructure and microhardness of the Cu-Al joint obtained by FSW. Optical and electron microscopy was used for the microstructure analysis and there was noticed the formation of a joint zone with a structure containing both Al and Cu. EDS analysis completes the microstructural analysis and confirms the presence of the two elements in the nugget zone. From the analysis of microhardness with the Vickers method it is noted an increase of hardness in the dissimilar welded joint zone (particularly in Cu) due to the achievement of a mixture of the anticlockwise rotational movement of the pin. FSW method proves to be a useful technique for joining dissimilar materials that are difficult to assemble with other conventional methods.