ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
High strain rates have a similar influence to large deformations on the refinement ofmicrostructure. In both cases, at large strains and high deformation rates, a strong tendency to formmicrobands is observed. It was found, that the width of the microbands is very sensitive to changesof the deformation parameters. It has been observed particularly, that in severely deformedmaterials, the width of the microbands is reduced to nanometric dimensions.Hydrostatic extrusion, which has been used in for the deformation of copper in the current work,strain rates exceeding 2 1 3.84 10 −⋅ε = × s were employed. In all the samples investigated, numerousmicrobands were found in the microstructure. The width of microbands varied from 20 to about400 nm. Thus, the width of some of the microbands exhibited dimensions typical of nanometricmaterials. Additionally, a special feature was the appearance of large areas of subgrains with anaverage dimension of about 200 nm. These areas were identified as recrystallized dynamically, orpost-dynamically.Large misorientations were found between the microbands and the surrounding “matrix’. Suchmisorientation facilitates the formation of high angle boundaries, which in turn contribute to thechanges of microstructure and mechanical properties. The mechanism for the creation of highmisorientation in the microband areas is probably different from that operating during the process ofdynamic recrystalization.The results confirm the possibility of obtaining a nanometric structure at lower deformation, but athigher strain rates
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/22/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.114.117.pdf
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