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.
