The Alloy Finemet Precipitation First Principles Simulation Of The Phase Structure And Magnetic Properties

Finemet alloys have very eccellent magnetic properties. Much effort has been devoted to understand the magnetic mechanism of the Finemet alloys since their birth.The soft magnetic properties in the Finemet alloys were influenced by the mirostructure, such as the grain size of bcc Fe-Si, the composition of the phases of bcc Fe-Si. The Cubic crystalline phase geometric structure has important influence on the soft magnetic property. The investigation of the bcc structure of alpha Fe (Si) is of important significance for the Finemet alloys.The structure and magnetic properties ofα-Fe(Si) phase precipitated in the Finemet alloys are investigated by first-principles calculation based on density functional theory, and some factors influencing on the magnetic properties ofα-Fe(Si) phase are discussed. Within the frame of the angle of electron spin, the magnetic properties ofα-Fe(Si) phases with different solubility of Si in the different sites of theα-Fe superlattice are calculated. The calculation results show that the spin-state density is one critical factor influencing on the magnetic properties. It is found thatα-Fe(Si) phase with Si in the vertex sites shows better magnetic properties than that with Si in the core sites. It is concluded that, with the increasing solubility of Si in theα-Fe(Si) phase, the appearance probability of Si in the vertex sites increases, which results in better magnetic properties. The calculation results agree with the previous experimental results. The present work is helpful for lightening the magnetism of the Finemet alloy.Up to now, much effort has been devoted to improve the magnetic properties of materials by alloying to attempt to understand the magnetic mechanism. In this paper, the structure and magnetic properties ofα-Fe(SiAl) phase are investigated by first-principles calculation based on density functional theory under the conditions of Al at the different sites and with different contents of Si in theα-Fe phase. The calculation results show that the solution of Al in theα-Fe(Si) crystal phase influences on the magnetic properties. First, the hybridization effects of Al and Si in the s and p orbitals lead to d orbital spin nearby the Fermi surface increases. As a result, the sum spins increase, leading to the increase of magnetic moment. Second, the size difference of the atoms results in the increase of lattice distortion due to the solution of Al in theα-Fe (Si) crystalline phase. As a result, the packing density of grains increases and the crystal size decreases, which is helpful for the deteriation of coercive force. Although Al is the non-magnetic element, the partial substitution of Nb by Al reults in improvement of the Finemet alloys'magnetic properties. The influence of partial substituting Al for Nb on the magnetic properiteis of the Finemet alloys'soft magnetic is mainly induced by replacing the Fe atoms into the nano-crystallineα-Fe (Si) phase.