تهيه آلياژهاي آنتروپي بالاي (FeCo1-xMn1+xZnCu, x = 0, 0.25, 0.50) به روش آلياژسازي مكانيكي و بررسي ويژگي‌هاي مغناطيسي آن‌ها

Abstract High entropy alloys (HEAs) are solid solutions composed of at least five major elements in equimolar or near equimolar proportions.The structure and physical and chemical properties of these alloys depend on the type and amount of their constituent elements.The purpose of making and investigating these new alloys, is to obtain materials with newer properties, which are unattainable with the traditional alloys, based on one or two main elements and other alloying elements.In this research, FeCo1-xMn1+xZnCu (x = 0, ± 0.25, ± 0.5, ± 0.75) high entropy alloys were made with high puritie iron, cobalt, manganese, zinc and copper powders by mechanical alloying method.To reach a single-phase solid solution, the equimolar FeCoMnCuZn alloy was selected and the raw material powders were milled for 5, 10, 15, 20, 25 and 30 hours. The X-ray diffraction (XRD) results showed that a single-phase FCC structure was obtained after at least 25 hours milling.Then, other samples were also milled for 25 hours, mixed with epoxy resin and formed into toroids.To eva‎luate the characteristics of the milled powders and toroidal samples, X-ray diffractometer (XRD) to phase characterization, Faraday balance to record magnetization-temperature curves and Curie temperature determination, Vibrating Sample Magnetometer (VSM) to plot hysteresis loops and saturation magnetization and coercive field determination and LCRmeter to determine magnetic permeability, were employed.The results show that saturation magnetization of the equimolar FeCoMnCuZn alloy is around 16 A.m2.kg-1 and does not change with the addition of manganese, while it increases by addition of cobalt. Coercivities ofthe alloys, FeCoMnCuZn, FeCo0.75Mn1.25CuZn, FeCo1.25Mn0.75CuZn, FeCo0.5Mn1.5CuZnand FeCo1.5Mn0.5CuZnare 4.4, 4.8, 4.8, 4.4 and 4 (kA.m-1) respectively and their Curie temperatures are 770, 750, 870, 650, 850, 560 and 800 °C, respectively.The relative magnetic permeabilities of the alloys varies from 4 to 23 in the frequency range of 200Hz - 1MHz and different temperatures from 25 to 800 °C. Also the permeability-frequency curves show that there is a negligible dependency of permeability on frequency for all samples, except the equimolar one.

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