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Contribution to the study of the amorphization mechanisms of intermetallic compounds by mechanical grinding; Contribution a l`etude des mecanismes d`amorphisation par sollicitation mecanique de composes intermetalliques

Abstract

This work aims at identifying the mechanisms responsible for amorphization of NiZr and NiZr{sub 2} compounds under ball-milling. In the first part, the effect of a localized deformation is studied: the deformation is produced by indentation on bulk samples, very high local strains can be achieved by this technique. The resulting microstructure is studied by transmission electron microscopy (TEM). No evidence for amorphization is found in these compounds, contrary to what is known to occur in silicon and germanium. Despite of their high brittleness, the NiZr and NiZr{sub 2} compounds accommodate the multiaxial localized stress by plastic deformation: dislocations multiplication and glide, micro-twinning. Dislocations (both perfect and imperfect) and micro-twins have been analysed into details for the first time. The twinning mechanism in NiZr{sub 2} has been elucidated. In the second part of this work, the microstructure of NiZr{sub 2} in the course of amorphization by ball-milling is studied by TEM observation are prepared by ultra-microtomy. The following evolution is observed: first, the material is fragmented and plastically deformed; the microstructure is refined by polygonation. Second, aggregates are formed by a fragmentation and sticking process, leading to a stationary size for the aggregates. The aggregates themselves are made of a  More>>
Authors:
Publication Date:
Jan 11, 1995
Product Type:
Thesis/Dissertation
Report Number:
CEA-R-5686
Reference Number:
SCA: 360103; 360102; PA: AIX-28:007111; EDB-97:007620; NTS-97:005751; SN: 97001715275
Resource Relation:
Other Information: TH: These (D. es Sc.).; PBD: 11 Jan 1995
Subject:
36 MATERIALS SCIENCE; AMORPHOUS STATE; NICKEL ALLOYS; ZIRCONIUM ALLOYS; MILLING; ELECTRON MICROSCOPY; INTERMETALLIC COMPOUNDS; MICROSTRUCTURE; NICKEL; PLASTICITY; SHEAR PROPERTIES; TWINNING; ZIRCONIUM
OSTI ID:
411258
Research Organizations:
CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Direction des Technologies Avancees; Paris-11 Univ., 91 - Orsay (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
Other: ON: DE97610157; TRN: FR9602567007111
Availability:
INIS; OSTI as DE97610157
Submitting Site:
FRN
Size:
132 p.
Announcement Date:

Citation Formats

Galy, D. Contribution to the study of the amorphization mechanisms of intermetallic compounds by mechanical grinding; Contribution a l`etude des mecanismes d`amorphisation par sollicitation mecanique de composes intermetalliques. France: N. p., 1995. Web.
Galy, D. Contribution to the study of the amorphization mechanisms of intermetallic compounds by mechanical grinding; Contribution a l`etude des mecanismes d`amorphisation par sollicitation mecanique de composes intermetalliques. France.
Galy, D. 1995. "Contribution to the study of the amorphization mechanisms of intermetallic compounds by mechanical grinding; Contribution a l`etude des mecanismes d`amorphisation par sollicitation mecanique de composes intermetalliques." France.
@misc{etde_411258,
title = {Contribution to the study of the amorphization mechanisms of intermetallic compounds by mechanical grinding; Contribution a l`etude des mecanismes d`amorphisation par sollicitation mecanique de composes intermetalliques}
author = {Galy, D}
abstractNote = {This work aims at identifying the mechanisms responsible for amorphization of NiZr and NiZr{sub 2} compounds under ball-milling. In the first part, the effect of a localized deformation is studied: the deformation is produced by indentation on bulk samples, very high local strains can be achieved by this technique. The resulting microstructure is studied by transmission electron microscopy (TEM). No evidence for amorphization is found in these compounds, contrary to what is known to occur in silicon and germanium. Despite of their high brittleness, the NiZr and NiZr{sub 2} compounds accommodate the multiaxial localized stress by plastic deformation: dislocations multiplication and glide, micro-twinning. Dislocations (both perfect and imperfect) and micro-twins have been analysed into details for the first time. The twinning mechanism in NiZr{sub 2} has been elucidated. In the second part of this work, the microstructure of NiZr{sub 2} in the course of amorphization by ball-milling is studied by TEM observation are prepared by ultra-microtomy. The following evolution is observed: first, the material is fragmented and plastically deformed; the microstructure is refined by polygonation. Second, aggregates are formed by a fragmentation and sticking process, leading to a stationary size for the aggregates. The aggregates themselves are made of a mixture of nanocrystalline (about 10 nm) material and coarser crystallites. As milling proceeds, the latter disappear to the benefit of the former. Once aggregates are 100% nanocrystalline, the amorphous phase appears and develops to the expense of the nanocrystalline phase. At late stages, small crystallites embedded in an amorphous matrix are observed. No massive chemical disordering is observed but a small amount can not be ruled out. It is suggested that amorphization occurs by chemical disordering at interfaces, induced by shear waves. (Author). 76 refs., 57 figs., 12 tabs.}
place = {France}
year = {1995}
month = {Jan}
}