Nanocrystallization and Magnetic Behaviour of Fe73.5- xCrxCu1Nb3Si13.5B9 amorphous alloys

Abstract—The present state of development and progress in various areas of materials science is closely related to the understanding of the properties of materials on their length scale. Understanding of the crystallization kinetics of magnetic amorphous / nanocrystalline alloys has enormous scientific and technological interest since the improvement as well as deterioration of magnetic properties sensitively depends on the degree of crystallization. Crystallization kinetics is often determined from Differential Scanning Calorimetry (DSC), Differential Thermal Analysis (DTA) and thermomagnetic analysis (TMA). In FINEMET with the composition Fe73.5Cu1Nb3Si13.5B9, ferromagnetic -Fe (Si) nanograins are formed from amorphous precursor by controlled annealing, which are coupled via exchange interaction through residual ferromagnetic amorphous matrix and exhibit ultrasoft magnetic properties. In the advanced stage of crystallization, iron boride phase is formed. Substitution effects have been studied for conventional FINEMET composition. Cr has been substituted for Nb previously as grain growth inhibiting element. Cr has also been substituted for Fe in order to study dilution effect of magnetic moment. In this study, series of amorphous alloys Fe73.5-xCrxCu1Nb3Si13.5B9 for an extended range of 0x17.5 has been studied thoroughly in order to observe crystallization and magnetic behavior due to Cr substitution for Fe using thermomagnetic measurement and differential scanning calorimety. Keywords—Crystallization, nanograin, magnetic moment