ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Technical purity Cu (99.95 wt%) polycrystals have been processed at room temperatureby equal channel angular pressing. The results of mechanical tests and the microstructurecharacterization by various experimental techniques are presented. The yield stress as well as thestrength were shown to increase with increasing strain and exceed the respective values of a coarsegrainedmaterial. The microstructure development and its fragmentation after ECAP wasinvestigated by the TEM and EBSD. The proportion of high angle grain boundaries was found toincrease with increasing strain reaching the value of 90% after 8 ECAP passes. Two kinds of defectswere identified in ECAP specimens by positron annihilation spectrometry (PAS): (a) dislocationswhich represent the dominant kind of defects, and (b) small vacancy clusters (so called microvoids).The main increase of defect density was found to occur during the first ECAP pass. PAS analysisindicated that in the specimens subjected to one ECAP pass the mean dislocation density ρD and theconcentration of microvoids cν exceeded the values of 1014 m-2 and 10-4 at.-1, respectively. After 4passes, the number of defects becomes saturated and practically does not change with increasingstrain
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.584-586.440.pdf
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