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Microstructures in Fe30Ni30Cu20P10Si5B5 melt-spun alloy ejected at various temperatures

100%

Ziewiec K. , Ziewiec A. , Prusik K.

2009

tom Vol. 37, nr 2

532-537

Purpose: The aim of the work is to study the influence of ejection temperature on the structure of Fe30Ni30Cu20P10Si5B5 melt-spun. Design/methodology/approach: A six-component Fe30Ni30Cu20P10Si5B5 alloy was arc-melt in argon protective atmosphere from of pure Fe, Ni, Cu elements and Fe-P, Fe-B, Ni-P, Ni-B master alloys and melt-spun in helium. The alloy was melt-spun in various temperatures. Morphology and chemical composition of the cross-section of the ingot and melt-spun ribbons were analysed with scanning electron microscope SEM with energy dispersive spectrometer EDS. The melt-spun ribbon was investigated by means of the transmission electron microscope (TEM). The melting range of the alloy was investigated by means of differential thermal analysis at the heating rate 20 K/min. Findings: The slow cooling rate resulted in the fractal-like structures formed by the Fe-rich regions and Cu-rich regions typical for the alloying system with a miscibility gap. The structures observed after rapid cooling were dependent on ejection temperatures of the alloy just before the melt spinning process. The lower ejection temperatures led to the formation of crystalline structures separated into Fe-rich and Cu-rich regions which were a result of rapid cooling within the miscibility gap. The higher ejection temperatures contributed to formation of amorphous/crystalline composite. The crystalline spherical precipitates were found to be predominantly Cu-base solid solution. Research limitations/implications: It has been shown that the multi-component Fe-Ni-Cu-P-Si-B alloy provides possibility of microstructure control of amorphous/crystalline composite due to miscibility gap. Practical implications: The work reports that the ductile phase can be introduced into the amorphous alloy by using a suitable ejection temperature control in a melt spinning process, providing possibility of controlling properties in glassy matrix alloys. Originality/value: The study provides original information about the primary structure of the arc-melt Fe30Ni30Cu20P10Si5B5 alloy as well as about the microstructure of melt-spun alloy using various ejection temperatures.

Corrosion of nickel aluminide in H2/H2S Gas mixtures.

70%

Godlewska E. , Żurek Z.

tom R. XIX, nr 4

933-936

Intermetallic compound beta-NiAl was sulphidized in H2/H2S mixtures with sulphur partial pressures raised to a -5th power Pa - 1 Pa at temperatures 1173 and 1273 K. The sulphidation runs, followed thermogravimetrically, were approximately parabolic. The calculated parabolic rate constants were very low and slightly increased with temperature and partial pressure of sulphur. The reaction products were examined by means of X-ray diffraction (XRD), energy dispersive X-ray (EDX) analyses and scanning electron microscopy (SEM). Aluminium sulphide and nickel-aluminium sulphospinel were predominant scale constituents in the applied experimental conditions. The scales were very thin and flaky. Generally two scale layers could be distinguished, the inner one was compact and outer one was discontinuous and consisted of needle-like or plate-like crystals. There was no evidence of internal sulphidation.