ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
Internal friction peaks observed in single or polycrystals are clearly due to a dislocationrelaxation mechanism. Because a sample observed by transmission electron microscopy (TEM)often exhibits in the same time various dislocation microstructures (isolated dislocations,dislocation walls, etc.) it is very difficult to connect the observed relaxation peak with a particulardislocation microstructure. Using isothermal mechanical spectroscopy (IMS), it is easier tocompare, for instance, the evolution of a relaxation peak with measurement temperature to themicrostructural evolution observed by in-situ TEM at the same temperatures. IMS was used tostudy a relaxation peak in a 5N aluminium single crystal firstly 1% cold worked and then annealedat various temperatures. TEM experiments performed in the same material at various temperaturesequal to the temperatures used for the damping experiments made possible to link this internalfriction peak with a relaxation effect occurring inside dislocation walls. In two other experiments ina 4N aluminium polycrystal and in a metal matrix composite with SiC whiskers, it is shown that theobserved relaxation peaks are connected to the motion of dislocations inside polygonizationboundaries in the first case and in dislocation pile-ups around each whisker in the second one.Theoretical models proposed to explain such relaxation peaks due to a dislocation motion inside adislocation wall or network are discussed
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.137.21.pdf
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