ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
Carbon-containing Fe - Si and Fe - Si - Al alloys were studied with respect to the carbonrelatedSnoek-type and Zener relaxation using different mechanical spectroscopy techniques. In allalloys the temperature-dependent profile of the Snoek peak, relative to that in pure iron, is modifiedon its high-temperature side by the substitutional atoms. At least two components, an Fe - C - Fe(which correspond to C atom jumps (diffusion) in areas where it is surrounded by Fe atoms only)and Fe - C - Me peaks, where Me = Si, Al, can be distinguished in the Snoek-peak profile. In bothbinary Fe - Al and Fe - Si and ternary Fe - Si - Al alloys, a higher annealing temperature prior toquenching leads to an increase in the Fe - C - Fe and a decrease in the Fe - C - Me component ofthe Snoek peak. Heating to 1173K and above often lowers the peak height due to thermal vacancies.Low-temperature (〈670K) ageing of quenched Fe - Si - Al and Fe – Si specimens reduces both theFe – C - Fe and Fe – C – Al / Si peaks. Ageing at T 〉 670 K changes the temperature- as well as theamplitude-dependent parts of internal friction due to a redistribution of carbon between solidsolution and dislocations. Both the Snoek-type peak height and the dislocation mobility – as can beconcluded from the slope of the amplitude-dependent internal friction – increase, and a new peakappears at temperatures higher than that of the Snoek peak, which probably is a Snoek-Köster peakresulting from the motion of weakly pinned dislocations. A Zener peak appears if the concentrationof substitutional atoms is 〉 6 at. %. The Zener peak relaxation strength is much lower in ternaryalloys than in the binary ones probably due to mutual compensation of elastic distortions inpresence of Al and Si atoms which are bigger and smaller, respectively, than Fe atoms
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.137.69.pdf
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