Zinn und Antimon in Legierungen

Ohne Zusammenfassung     

A new program for DSC purity analysis

DSC purity determinations have become very popular today [3]. The latest edition of the Mettler software package for thermal analysis, TA72.S GraphWare, now comprises a powerful purity evaluation program. It is based on the simultaneous calculation of the mole ratio of the sum of the eutectic impurities, the melting point of the pure component, the melting point of the substance present and the linearization term. The portion of the melting curve investigated is selected appropriately.Experience has shown, that the applied heating rate is a very important parameter which influences the duration of the measurement and also the possible exposure to elevated temperature where decomposition can become a problem and last but not least the accuracy of the calculated impurity value.

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Zusammenfassung Die DSC-Reinheitsbestimmung ist heute eine weit verbreitete Methode, die mit einer einzigen Messung und unter Verwendung geeigneter Auswerteprogramme eine Bestimmung der absoluten eutektischen Reinheit einer Probe zulÄsst. Gleichzeitig können weitere thermodynamische Daten bestimmt werden, wie Schmelzpunkt der Probensubstanz und der reinen Hauptkomponente und die Schmelzenthalpie der Probe.Durch experimentelle Befunde konnte gezeigt werden, dass die Wahl der Aufheizrate kritisch ist in bezug auf die Genauigkeit und die Signifikanz der ermittelten Daten.

     

CEMS and DCEMS investigations of Al-implanted iron

-Fe surfaces were implanted with a nominal dose of 5×10¹⁷ Al ions/cm² at 50 keV and a current density of about 3.7 A/cm². Samples of different shapes and thicknesses have been used in order to test the influence of heat flow from specimen to target holder during implantation. Integral and energy differential (depth-selective)⁵⁷Fe conversion electron Mössbauer spectroscopy (CEMS and DCEMS) were employed. The spectra indicated a magnetic phase characterised by a broad hyperfine field distributionP(B _hf), a non-magnetic phase, and -Fe. The relative intensity of the non-magnetic phase was enhanced if the thermal contact during implantation became worse. An energy dependence of DCEM spectra in the L-electron range was observed. Model calculations using L-electron weight functions and experimental concentration profiles obtained by secondary neutral mass spectroscopy (SNMS) yielded fair agreement between calculated and experimental phase signals. The results demonstrate that the non-magnetic Fe-Al alloy phase with high Al concentration is located closer to the surface than the magnetic alloy phase, which extends to much larger depth than expected.