Ispitivan je uticaj strukturnih promena izazvanih primenom spoljašnjih parametara (toplotno
dejstvo, magnetno dejstvo, mehaničko naprezanje) u toku procesa strukturne relaksacije i
kristalizacije na funkcionalna svojstva tri legure na bazi gvožđa, različitog hemijskog sastava:
Fe89.8Ni1.5Si5.2B3C0.5, Fe81B13Si4C2 i Fe73.5Cu1Nb3Si15.5B7. Legure su dobijene brzim hlađenjem
rastopa na rotirajućem disku (melt-spinning). Uzorci su bili u obliku trake dužine 20 cm, širine 2 mm
i debljine 3 μm.
Strukturna stabilnost i strukturne transformacije legura ispitane su primenom difrakcije Xzraka.
Pokazana je egzotermna termička stabilnost ispitivanih legura u temperaturskom intervalu od
200C - 7000C, primenom diferencijalne skanirajuće kalorimetrije (DSC). Ovaj temperaturski
interval obuhvata relaksaciju deformisane strukture, gubitak feromagnetičnosti i konačno
kristalizaciju, rekristalizaciju i rast kristala formiranih faza. Proces kristalizacije obuhvata
formiranje različitih stabilnih i nestabil...nih faza u zavisnosti od hemijskog sastava ispitivanih legura.
Ispitana je kinetika procesa strukturne relaksacije ovih legura, pri različitim naprezanjima i
temperaturama odgrevanja. Zatim je ispitan uticaj strukturne relaksacije na promenu gustine stanja
elektrona na Fermi-evom nivou. Pokazano je da strukturne promene imaju velikog uticaja na
električna i magnetna svojstva ovih legura. Utvrđeno je da relaksirana amorfna struktura legure
poseduje znatno bolja električna i magnetna svojstva kako u odnosu na polaznu leguru, tako i u
odnosu na iskristalisalu leguru sa stanovišta mogućnosti praktične primene. Takođe je ispitana i
mogućnost primene ovih legura kao senzora sile.
Uspostavljena je jasna korelacija strukturne promene – funkcionalna svojstva i dato
fundamentalno tumačenje međuzavisnosti strukturna relaksacija – promena gustine stanja elektrona
na Fermi-evom nivou – električna svojstva – magnetna svojstva, što je i cilj ove disertacije.
The effect of structural changes was investigated, induced by the application of external
parameters (thermal influence, magnetic influence, mechanical strain) within the structural
relaxation process and crystallization, over the functional properties of three Fe-based alloys of
various chemical content: Fe89.8Ni1.5Si5.2B3C0.5, Fe81B13Si4C2 and Fe73.5Cu1Nb3Si15.5B7. The alloys
were obtained by rapidly quenching of the melt on a rotating disk (melt-spinning technique). The
samples were ribbon-shaped, 20 cm long, 2 mm wide and 3 μm thick.
The structural stability and structural transformations of the alloys were investigated by X -
ray diffraction. Exothermal stability of the investigated alloys in the temperature range from 200C to
7000C was determined, by the differential scanning calorimetry method (DSC). This temperature
range presumes relaxation of deformed structure, the loss of ferromagnetic properties and finally
crystallization, recrystallization and growth of the crystallites ...of formed phases. The crystallization
process includes the formation of various stable and unstable phases depending on the chemical
content of the investigated alloys. The kinetics of the structural relaxation process of these alloys
was investigated at different strain intensities and annealing temperatures. Furthermore, the
structural relaxation effect on the electron state density change at Fermi level was investigated. It
has been shown that the structural changes have significant effect on electrical and magnetic
properties of these alloys. It has been determined that the relaxed amorphous structure of the alloy
possesses far better electrical and magnetic properties as compared to both the as-cast alloy and the
crystallized alloy, from their technological applicability aspect. In addition, the possibility of
application of these alloys as power sensors has also been investigated.
A clear correlation of structural changes – functional properties has been determined, as well
as the given fundamental interpretation of the interdependence structural relaxation – electron state
density change at Fermi level – electrical properties – magnetic properties, which is the aim of this
dissertation.
