Nowadays, many applications involved in using similar materials to be combined required engineering application. It is a challenging thing to achieve as every material has its own thermal, mechanical and electrical properties which need to be considered before fabrication is done. FSW is the best choice to join dissimilar material such as aluminium alloy and copper. Consequently, poor joint strength at welded part that can be found in literature review by FSW has been found as a problem. The objectives of this paper are to investigate the microstructure of the vertical compensation friction stir welded joint and to study the effect of filler material on the strength of the welded joint. The scope of study in this project is within the aspect of FSW, aluminium alloy, copper alloy, microstructural examination and tensile test. The manipulated parameter in this project is the filler materials. The type of joint that was used is butt joint with filler in between 2 base materials. The welded samples were cut to execute for microstructural examination and tensile test according to its standard. The microstructural properties of the joints were examined optical microscope (OM) and tensile test by using UTM. Experimental test was done to find out the most influencing factor which is filler material factor to determine the strength of VCFSW. After the tensile test, the welded joints were tested with microstructure analysis to study the structure of material under OM and SEM. The grains in the DCZ experienced recrystallization and changed in grain boundaries size. The tensile strength for fillers of AA1100, AA7075 and Cu C1100 obtained 101.402MPa, 127.28MPa and 11.308MPa respectively. In conclusion, the joint between AA7075 filler and AAA6061 plates obtained the strongest joint of all the joints with 127.28 MPa peak stress. The joint between copper filler and AA6061 plates obtained the least strength with 11.308MPa peak stress. Finally, few recommendations were inserted for further study of regards of joining dissimilar materials.
