High Entropy Alloys have become popular with scientists in recent years due to their unique structure and properties. These materials contain 5 to 13 basic elements with atomic percentages equal or approximately equal, which increase entropy and high stability and other properties. Many applications have been defined for these materials, especially due to their high temperature stability. The purpose of this study is to fabricate a high entropy alloy CuFeNiMnTi and to investigate the microstructure and mechanical properties of the joint similar to this alloy. In this regard, first the high entropy alloy of CuFeNiMnTi was made by vacuum induction melting method, then the cast alloy was welded by tungsten gas arc welding method using ER309l, ERNiCr-3 and CuFeNiMnTi filler metals. To study the microstructure of different welding areas, including base metal, heat affected zone and weld metals, electric engraving method using different solutions has been used. The microstructure of the samples was also characterized by light microscopy, scanning electron microscopy and X-ray spectroscopy analysis. Tensile and microhardness tests were used to eva‎luate the mechanical properties. Also, after performing the fracture tensile test, the failure levels were checked. The high entropy alloy microstructure of CuFeNiMnTi consists of two FCC phases rich in copper and nickel, the lava phase Fe2Ti, FeTi and NiTi. The microhardness of alloy was measured 500HV0.3N. The results of the tensile test indicate the final tensile strength of about 386 MPa. The results of X-ray diffraction and X-ray energy separation spectroscopy in the sample welded with CuFeNiMnTi filler metal confirm the presence of all cast base metal phases and only the copper-rich FCC phase in the weld metal structure was reduced compared to the base metal. Also, the weld area had a finer dendritic structure than the base metal. The microstructure of the 3-ERNiCr filler weld zone is completely austenitic with frozen niobium-rich sediments. The ER309l welding metal microstructure includes Fe2Ti lava phase, austenite phase, copper-rich FCC phase and delta ferrite. CuFeNiMnTi filler metal with an average microhardness of 518 Vickers produced higher microhardness than the base metal and other weld metals. on the other hand, The filler metal ER309l, produced the lowest average microhardness (277 HV0.3N) among the weld metals. The microhardness of the ERNiCr-3 weld metal was not significantly different from that of the base metal due to the formation of niobium-rich fine deposits. Fracture of welded specimens occurred from the heat affected area and Surface fracture of all the jointsindicate the occurrence of completely brittle failure.

فتح الله كريم زاده، محمد حسن عباسي

ابوذر طاهري زاده، مهدي رفيعائي