Vortrag: Anelasticity of iron-based ordered alloys and intermetallic compounds

Vortrag im Fakultätskolloquium am 27.6.2007

Im Rahmen des Fakultätskolloquiums findet am
Mittwoch, dem 27.6.2007, um 16 Uhr s.t., im Kleinen Horst-Luther-Hörsaal, Leibnizstrasse 8,
folgender Gastvortrag statt:

Anelasticity of iron-based ordered alloys and intermetallic compounds
Prof. Igor S. Golovin, Physics of Metals and Materials Science Department, Tula State University, Russia

First, an introduction to anelastic behaviour of metallic materials will be given, and a method of mechanical spectroscopy will be introduced for better understanding of relaxation and hysteretic phenomena. Some examples of anelasticity due to different structural defects in disordered Fe-based alloys (Fe-Al, Fe-Ge, Fe-Si,) will be considered with special emphasis to the analyses of the carbon Snoek-type relaxation with respect to “carbon - substitute atom” interaction in iron. The effect of ordering of substitute atoms on anelasticity in Fe-based alloys is analysed in terms of substitute atom content and type of order also considering sources for high damping capacity of some compositions. Anelastic behaviour of iron-based D03 (e.g. Fe3Al) and D019 (e.g. Fe3Ge) intermetallic compounds is discussed in a wide range of temperatures and vibrating frequencies to identify the contribution from interstitial and substitute atoms, dislocations and vacancies. Similar effects in ternary iron-aluminium based alloys Fe-Al-Me (Me = metal: Co, Cr, Ge, Mn, Nb, Si, Ta, Ti, Zr) are analysed.  The study of elastic and anelastic behaviour is supported by structural characterisation (XRD, TEM, DSC, magnetometry). The following anelastic phenomena are included into this talk: the Snoek-type (caused by interstitial atom jumps in Fe-Me ferrite) and the Zener-type (caused by reorientation of pairs of substi-tute atoms in iron) relaxation, the vacancy and dislocation related relaxations, magneto-mechanical damping. A family of low-temperature peaks recorded due to self interstitial atoms in ultra fine grained intermetallics is used to characterise the thermal stability of severely deformed (Fe,Me)3Al. These effects are discussed using data available from literature and author’ experimental data in the Hz and kHz ranges of vibrating frequencies for Fe-Al, Fe-Ge, Fe-Si binary and several ternary systems in disordered and ordered ranges of the phase diagrams including intermetallic compounds of Fe3Me type.

Nachrichtenalter: 08.05.2007 14:27


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