چكيده به لاتين
High entropy alloys are multi-component alloys that contain at least 5 and at most 13 main elements with approximately equal atomic percentages between 5 and 35%. In other words, high entropy alloys are solid solutions that have high atomic substitution that increases entropy and high stability and other properties.The purpose of this research is to manufacturing an alloy with high entropy and study its mechanical and metallurgical properties. For this purpose, high entropy alloy Al0/8CoCrFeNi was made by vacuum arc remelting (VAR) method, then the structure was homogenized. Due to the non-rollability of the high entropy alloy and according to the results of the electron diffraction (XRD) test as well as the thermo calc software, the sample was annealed in three temperature classifications of 700, 1000 and 1300 centigrade. The alloy structure at 700°C includes FCC, BCC and Sigma phases, 1000°C includes FCC and BCC phases, and 1300°C include BCC single phase. In this research, we intend to investigate the mechanical and metallurgical properties of this alloy by performing various analyses, including mechanical and metallurgical analyses. Studies of binary/tripolar phase diagrams show that such multi-element alloys may form several tens of phases and intermetallic compounds, resulting in complex and brittle microstructures that are difficult to analyze. However, in contrast to this Expectations, experimental results show that the higher entropy of mixing in these alloys facilitates the formation of solid solution phases with simple structures and thus reduces the number of phases. In addition, the production of high entropy alloys is generally based on trial and error, but their production does not require special techniques and equipment, which indicates the ease of implementation for mass production. Therefore, based on the predictions and comparison of different properties, the Al0/8CoCrFeNi sample, due to the single-phase structure, is a suitable proposal in line with the research approach, which is used in gas turbine blades. For this purpose, to check the mechanical properties, tension, pressure and fracture toughness tests and microhardness measurements were performed. The results of microhardness measurement showed that according to the structure, the maximum hardness is at 1300 and equal to 649 HV0.1, which is in accordance with the results of the thermo clac software, according to the existing structural phases. In the investigation of the metallurgical properties, in addition to the analysis with the thermo clac software, X-ray diffraction (XRD), quantometry, scanning electron microscope (SEM) analysis, examination of the fracture surface of this alloy, X-ray energy diffraction spectrometry and grain size analysis are carried out. . According to the comparison of the grain size, in the three mentioned temperature classifications, with increasing temperature, the grain size increases to 174.5 m at the temperature of 1300 ℃.
