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Structural analysis of austempered ductile iron obtained by Mössbauer spectroscopy

Hanc A., Binczyk F.

Archives of Materials Science and Engineering

2008

Vol. 31, nr 2

101-104

Purpose: The composition of metallic matrix in ductile iron as-cast and after austempering at temperatures of 280, 330 and 380°C (ADI) was examined. Design/methodology/approach: The study presents the results of these examinations obtained by Mössbauer spectroscopy. Findings: Using calculated values of the parameters of hyperfine interactions (isomeric shift IS, quadrupole splitting QS and hyperfine effective magnetic field H), isolated by deconvolution of the experimental spectrum, the constituents of the metallic matrix were identified in terms of both quantity and quality. Research limitations/implications: The measured values as well as the data compiled in literature indicate that component Z1 (the, so called, Zeeman spectrum sextet) is related with 57Fe atoms present in the structure of ferrite α1 (I stage of γ0→α1 + γst transformation), component Z2 is typical of ferrite α2 (II stage of γst→α2 + carbides transformation), while component Z3 has its origin in 57Fe atoms seated in the structure of carbides (Fe3C, Fe2C or Fe2,4C). Practical implications: analysis of the parameters of hyperfine interactions describing the non-magnetic components (L and Q) it has been proved that they are typical of austenite. Originality/value: In the case of ADI, the determination of the composition of metallic matrix by Mössbauer spectroscopy is much more precise (the limit is the resolution power), because the experimental spectrum describes an overall volume of the examined specimen, and not only its surfaces, as does the traditional quantitative metallography.

Structure and properties of the powder obtained from the amorphous ribbon

Konieczny J., Dobrzański L. A., Frąckowiak J. E.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 18, nr 1-2

143--146

Purpose: The aim of the work is to investigate the magnetic properties of the cobalt based Co68Fe4Mo 1Si13.5 B13.5 amorphous alloy subjected to the isothermal annealing, high-energy milling and to a combination of these two technologies. Design/methodology/approach: The powder test piece obtained from the input amorphous ribbon in high-energy ball milling. Distributions of the magnetic hyperfine P(H) fields were determined for spectra smoothed in this way, by using the HFQS program, employing the Hesse-Rübartsch method. The diffraction examinations and examinations of thin foils were made on the JEOL JEM 200CX transmission electron microscope. Observations of the structure of powders were made on the Opton DSM-940 scanning electron microscope. Findings: The analysis of the magnetic properties test results of the of the Co68Fe4Mo 1Si13.5B13.5 powders obtained in the high-energy ball of milling process proved that the process causes significant decrease in the magnetic properties. The structure and magnetic properties of this material may be improved by means of a proper choice of parameters of this process as well as the final thermal treatment. Research limitations/implications: For the powders, further magnetical, structure and composition examinations are planed. Practical implications: The amorphous and nanocrystalline metal powders obtained by milling of metallic glasses feature an alternative to solid alloys and make it possible to obtain the ferromagnetic nanocomposites, whose shape and dimensions can be freely formed. Originality/value: The paper presents influence of parameters of the high-energy ball milling process on structure and magnetic properties of soft magnetic powder materials obtained in this technique. The paper compares structure and magnetic properties of the Co 68Fe4Mo 1Si13.5B13.5 alloy obtained in high-energy ball milling process and melt spinning technique.