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:
A positron annihilation study of free volumes was performed on Cu-Zr and Al-Sm alloysin the course of repeated cold rolling (RCR) in order to contribute to the microscopic understandingof the complex processes of solid-state amorphization and nanocrystallization. In addition topositron lifetime spectroscopy, which yields information on the size of free volumes, twodimensionalDoppler broadening technique was applied in order to study the local chemicalenvironment of free volumes on an atomistic scale. Both in Cu60Zr40 and Al92Sm8 a characteristicvariation of the chemical environment of free volumes with the number of folding and rolling(F&R) cycles could be observed. In the first (Al-Sm) and intermediate state (Cu-Zr) of F&R, freevolumes with an enhanced amount of Sm or Zr content in the local environment occur, indicatinginterfacial segregation or the formation of solute-vacancy complexes. Upon further F&R cycling, acomplete (Cu-Zr) or partially amorphous structure (Al-Sm) is obtained with the free volumesexhibiting a chemical environment characteristic of the average chemical composition. In contrast tomelt-spun or ball-milled amorphous alloys, free volumes of the size of a few missing atoms arefound in amorphous alloys prepared by RCR presumably due to strong athermal conditions of F&Rcycling
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.584-586.209.pdf
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