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Helical dislocations produced by low temperature thermocycling in a Ti–Al Alloy
Author(s) -
Lavrentev F. F.,
Pokhil YU. A.,
Dudko P. P.
Publication year - 1982
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170170904
Subject(s) - materials science , dislocation , alloy , transmission electron microscopy , allowance (engineering) , anisotropy , condensed matter physics , crystallography , grain boundary , composite material , metallurgy , optics , microstructure , chemistry , nanotechnology , mechanical engineering , physics , engineering
By transmission electron microscopy (TEM), the structural state of a Ti–Al alloy subjected to low temperature thermocycling from 300 to 77 K has been investigated. As the result of this observation, helical dislocations were revealed with the density 10 9 cm −3 . These were generated mainly by grain boundaries or subboundaries. Their formation is thought to be associated with thermomechanical stresses arising during thermocycling. Thermomechanical stresses at the interface of neighbouring grains, estimated with making allowance for the anisotropy of the linear expansion coefficient, appeared to be about 7 kg/mm 2 . It is assumed that helical dislocation formation is one of the ways in which local internal stresses are relieved.