Síntesis y Caracterización de Aleaciones Magnetocalóricas Gadolinio-Fe
Rodríguez-Pereira, Ana Maria
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This investigation has as main objective to characterize the magnetocaloric effect of Gadolinio-Fe alloys made by casting techniques of suction casting and and rapid casting; and determine which of the processes generates the best magnetic properties. The samples analized were the ingot direct from the supplier, Gadolinio ingot manufactured by Suction Casting, Gadolinio, strips of Gadolinio manufactured by fast casting and the alloy of Gadolinio 96% and 4% Fe, generated by fast casting. These were analyzed by the techniques of X-ray diffraction, optical microscopy and scanning and transmission microscopy (SEM and TEM). They were also analyzed using the technique of vibrating sample magnetometry, and from the results obtained hysteresis curves were build. This technique also allowed to characterize the magnetocaloric effect of the samples, based on the obtained in termomagnetización curves and entropy change over temperature. From the analysis of the thermomagnetic curves, it possible to concluded that all the samples analyzed have the transition from a magnetic to a non-magnetic behavior in a temperature range of 289-292K. While analyzing the entropy change curves over temperature, it showed that the property passes through a maximum, which coincides with the Curie temperature of each sample, and the Magnetic Entropy varies in a range between 4.0 and 5.5 J / kgK, which is consistent with reported values of entropy for pure Gadolinio. From all the samples analyzed, the Gadolinio ingot manufactured by the suction casting is the process that generates the best Magnetic Properties as this alloy showed the highest value of saturation magnetization at room temperature (89.7107 emu/g) and the maximum magnetic entropy (5.5 J / kg / K).
Proyecto de Graduación (Licenciatura en Ciencia e Ingeniería de los Materiales). Instituto Tecnológico de Costa Rica. Escuela de Ciencia e Ingeniería de los Materiales, 2016.