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Owing to the relative abundance of its constituent elements and large MCE observed near room temperature, the AlFe2B2 system has attracted much attention recently 1. As an alternative to current rare earth materials, AlFe2B2 promises the realization of cleaner, energy efficient refrigeration technologies based on phenomena associated with MCE 2. Additionally, excess Al is believed to generate phase impurities which can change the observed MCE properties of this system 3. By dissolving certain impurities in acid, a significant enhancement of the MCE properties of this system have been observed 4. Considering this behavior, we have studied the effect of acid treatment on the magnetic, magnetocaloric, and transport properties of Al0.85+xSi0.15Fe2B2 (x = 0.2, 0.4). The goal was to explore the possibility of enhancing the MCE properties of the materials by adding excess aluminum and subjecting them to acid treatment after annealing. The samples were prepared by arc melting followed by drop-casting. The drop-casted samples were annealed followed by acid treatment. The alloys were characterized by x-ray diffraction, scanning electron microscopy, dc magnetization, and electrical resistivity measurements. The second order ferromagnetic phase transitions were observed near room temperature (~298 K – 315 K) and peak magnetic entropy changes (-ΔSM) of more than 4 J/kg K were observed for a field change of 5 T. The details of phase purity, microstructure, magnetic, and transport properties of the acid treated and the drop casted annealed materials will be presented.
