Abstract
Novel type of soft magnetic alloy, Supermalloy (Ni-Fe-Mo)/alumina (Al2O3) is designed to be obtained by reaction spark plasma sintering of Al-Supermalloy surface oxidized particles. The nominal composition of the alloy used for the compacts synthesis is Ni70.5Fe18.8Mo4.7Al6. Two techniques have been used for surface oxidizing, heat treatment in a mixture of air and argon and powder immersion in HCl solution. Both types of oxidation techniques lead to the formation of a layer of oxides on the particles surface, evidenced as being mainly iron oxides, such as hematite-Fe2O3 and magnetite-Fe3O4. The composite particles Al-Supermalloy@oxides have been further subjected to spark plasma sintering at 900 ºC for 10 min, in order to densify and promote the reaction between Al-Supermalloy and iron oxides to form a matrix of alumina. The aluminum from Al-Supermalloy reacts with the oxides that cover the particles resulting in a oxide matrix that is formed mainly by alumina. The alumina matrix for the compact obtained from powder covered by heat treatment in argon and air mixture (10/1 vol ratio) is more consistent as compared to the compact obtained from the powder covered by immersion in HCl solution. The magnetic properties in DC and AC for the compacts obtained from powder oxidized in argon and air mixture at temperature are more consistent as compared to the other compact. The samples have been investigated in the light of scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), Fourier transformed infrared spectroscopy (FTIR), DC an AC magnetic properties on sintered compacts and electrical resistivity.
Published Version
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