Investigation of the effect of additive elements on microstructure and mechanical properties of solder alloys

This doctoral thesis study includes the investigation of the effects of alloying elements used in the production of the brazing additive metal, which is widely used in the industry, and the metallurgical effects of the use of indium element to reduce the amount of silver, which is costly. The use of silver-containing brazing additive metals creates economic difficulties due to its increasing cost. For this reason, the use of indium instead of silver in the brazing additive metal will be an important development for both the industrialists and the scientific community. This thesis study explores the potential of indium element to reduce the cost of brazing additive metal. In this study, with reference to the solder filler metal containing 45% Cu, 35% Zn, 20% Ag, the amount of silver in its content was reduced gradually until it was reduced to 0%, and %In was added at a decreasing rate. While the %Cu and %Zn amounts have not changed, only %Ag has been decreased, while the %In amount has been increased. The production of solder metals was carried out by calculating the weights of the alloying elements determined in the atmospheric environment and melting them in the induction furnace. The obtained 9 different samples were used in brazing of St37 steel. Then, microstructure investigations, thermoanalysis examinations, SEM, EDS, XRD tests, microhardness measurement and single point overlap slider test were performed. As a result of the tests and examinations, it was concluded that although the amount of silver decreased by 10%, 10% indium addition showed similar breaking strength with the reference sample, indium-free and 20% silver-