Study of the magnetic permeability and magnetoresistance of Fe74.5Nb2Si13.5B9Ag1 alloy

Abstract

Nanocrystalline alloy in the form "f ribbon with the composition of FC74,NblSi",B9i\g, pJ"cpared by rapid quenching method has been ,tudicd for strltClural, c'.ystaili~alion bcllavi"l', n~nocl'ystalliLatiol\ j()rmation, e1eetl'ical rcsi,tivity and son magnetic properties, Thc amorphosity of the sample has been conJ1rmcd by X-ray diffraction technique (XRO). The kinetics of crystallilation was studicd by DiITcremial lhermal Amilysis (DTA), M"gnclk propcrties have been studied by Vibrating Sample Magnctometel' (VSM) and impcxlancc analyzer. Magnetoresistivc properties havc been studied as a function of temperature and magnctie field. The activation cnergy of cry~tallizalion of (I-Fe (Si) and Fe-B phase has been obtained as1.64 and 1.94 eV rcspcetively, Strong dependence of magnetic pcnneability and magnctie loss factor with annealing tcmperature and annealing time has been observcd, The initial pcrmeabilily increu,es with thc increase of annealing tempcrnlurc due to struclurul reluxaliun und sharp fall of initial permcability i.1 observed bcyond the crystuitilaliOll lempemtlll'e. Maxillllllll vullie oj" initial permcability is reached within 5-8 minulc,>_The inilial pcrmeability for the annealed sample was found to be 8n6 a~ compared to 852 for its amorphous counlerpal't. Curic tempcralme of thc amorphol" phase has bccll detcrmined from lempemture dependence of initial permcability. Saturation magnclizaliol1 mcasured 011 the amorpbous and annealed snmples gradually increascs On annealing up (0 the crystallization temperature, beyond, which lhe m"gneti~atiol1 decl'eascs. The results are intcrpretcd on the basi, of in"nersiblc stl'uctural relaxation as well as enrichment of thc mlllograills with Si. T~l1lpcratur~ depcndence of permeability of thc I1anocryst~lIizcd Slllllpics sI10\vs the supc, feL"l'om~gneticbchavi{lr above T:m of the umorphous m"trix, which dcpclld, on (ile volumc 1i.a~tionof the nanograins form~'{1 by cOlllmlled ullnealing. I(esi,tivily decrcases ab{lvC Curie tempcl'ature and Magnctoresistanee sl1{lw ,ignifienlll anomalous bchavior due to magnetic and structural phase transition, A good correlation of transition tempcratures and magnctic properties has been observed betwccn alltbe measuremcnltechniques such as XRD, DTA, temperalul"\: dependence of permeability, satumtion magnetization, cleetl'icalrcsistivity and magnclorcsistancc measuremcnts.