Alicja Zaluska

Crystallization characteristics of amorphous Fe-Si-B alloys

Crystallization of soft magnetic Fe-Si-B glasses was investigated by transmission electron microscopy and X-ray diffraction. Electron micrographs of the successive crystallization stages of some Fe-Si-B glasses were obtained and the morphology variations for different alloy compositions were determined. The compositional dependence of the crystallization mode exhibited by the Fe-Si-B glasses was analysed, and on this basis some suggestions about crystallization rules in these glasses are proposed. Two kinds of iron—silicon phases occurred, depending on the Fe-Si-B alloy composition: bcc Fe(Si) solid solution and an ordered solid solution on the structural basis of Fe3Si iron suicide. It is suggested that the metastable Fe3B phase (observed during crystallization of only few glasses) was not a simple consequence of boron content. Crystallization of the Fe3B phase was related to the formation of the iron—silicon phase which was produced during the first crystallization stage.

Current pulse heating of CoFeSiB metallic glass

Abstract A non-conventional method of heat treatment, current pulse heating, was used to study the crystallization of CoFeSiB metallic glass. Pulse heating provides very high heating rates and therefore crystallization processes which occur during pulse heating of metallic glasses differ from the corresponding processes observed in conventionally annealed glasses. Pulse-annealed samples were investigated by differential scanning calorimetry. Measurements of electrical resistance were also performed.

Crystallization of the amorphous Fe45Ni35Si10B10 alloy due to pulse heating

The effect of rapid heating on the stability of amorphous Fe45Ni35Si10B10 is studied in detail by Mössbauer spectroscopy. Structural relaxation as well as formation of crystalline α-Fe and γ(FeNi) is observed, depending on the heating and cooling conditions applied.

Rapidly quenched composite materials

Abstract The melt-spinning technique was used to prepare composite materials consisting of metallic glass matrix and the second phase in the form of particles. The particles were injected into the melt puddle using a specially constructed pressure nozzle. Ribbons with a Ni 75 Si 8 B 17 matrix and 3–5% fractions of a commercial SiC, SiCNi i.e. chemically covered by nickel and B 4 C were obtained. Mechanical testing and SEM observations were carried out. Results differed significantly; the wettability of the particles by liquid alloy essentially determines tensile strength of the rapidly quenched composite materials. Also interphase faces between particles and the amorphous matrix play an important role in the initiation of fracture.