Abstract
Iron-based amorphous alloys have been a focus of considerable scientific interest in recent years, both from fundamental and practical point of view. Comprehensive study of Fe75Ni2Si8B13C2 amorphous alloy investigated its thermal stability and thermally induced changes of the electrical, magnetic and mechanical properties and correlated them with microstructural changes. The alloy was investigated in 25-1000?C temperature range. Thermally induced structural transformations had been investigated using the DSC and the thermomagnetic measurements, revealing that the alloy exhibits the Curie temperature, glass transition, multi-step crystallization and recrystallization. The crystallization kinetics was determined, under non-isothermal conditions, to include three processes, corresponding to crystallization of ?-Fe, Fe3B and Fe2B phases, respectively. Microstructural analysis using the XRD and the M?ssbauer spectroscopy suggests that Fe3B acts as an intermediate in the formation of Fe2B. The microstructure was investigated on both the surface of the alloy ribbon and on the cross-section, using SEM to determine structural changes of the alloy after thermal treatment. Additionally, the XRD spectra were analyzed to determine the change in microstructural parameters of the alloy caused by the thermal treatment and the structural transformations. The M?ssbauer spectroscopy was used to determine the distribution of iron atoms between the individual crystalline phases and the amorphous matrix. The functional properties were investigated using measurements of the magnetic susceptibility, electrical resistivity and microhardness and these results were correlated with changes in the microstructural parameters (average crystalline size, microstrain) and the phase composition. The measurements were performed, where possible, both during heating cycles to observe the change of these properties with temperature, and at room temperature, after individual heating cycles to determine the change in properties caused by annealing at different temperatures.
Highlights
Merenja mikrotvrdoće po Vickers-u su izvršeni sa opterećenjima od 0,4 N i vremenom opterećenja od 10 s, u temperatorskom opsegu 25−600 °C
Difraktogrami X-zraka (XRD), slika 1, Fe75Ni2Si8B13C2 amorfne legure pokazuju izražen halo pik u 2θ opsegu od 40−50° i jedan slabiji u opsegu 75−85°
Ovo ilustruje sposobnost ove metode da pokaže razliku između amorfne strukture okarakterisane uređenošću na blizinu od strukture kristalnih faza koje sadrže gvožđe [17,18,19]
Summary
Amorfne legure na bazi gvožđa su, već duže vreme, predmet velikog naučnog interesovanja [1,2,3,4,5,6,7,8,9,10]. Najnovija istraživanja su pokazala da je moguće napraviti magnetne amorfne legure gvožđa koje ne sadrže bor [3] čija su svojstva veoma slična poznatim legurama sa dobrim magnetnim svojstvima koje sadrže bor. Fizička svojstva ovih materijala značajno zavise od njihove mikrostrukture [9,10], uključujući stepen kristaličnosti i veličinu kristalita, pa se kontrolom procesa kistalizacije može omogućiti dobijanje materijala ciljanih svojstava. Zbog toga je poznavanje termičke stabilnosti, mehanizma i kinetike procesa kristalizacije ovih materijala neophodno, kako zbog njihove primene kao funkcionalnih materijala, tako i zbog njihove moguće primene kao prekursora za sintezu hibridnih kristalnih-amorfnih materijala. Sveobuhvatna ispitivanja pokazala su da ispitivana legura pod uticajem zagre-
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