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Experimental and theoretical study of phase transitions under ball milling; Etude experimentale et modelisation des changements de phases sous broyage a haute energie

Abstract

The aim of this work was to determine how phase transition s under ball-milling depend on the milling conditions and to find out if one can rationalize such transitions with the theory of driven alloys. We have chosen two phase transitions: the order-disorder transition in Fe Al and the precipitation-dissolution NiGe. In the case of Fe Al we have found that the steady-state long range order parameter achieved under ball milling intensity; moreover the same degree of order is achieved starting from an ordered alloy or a disordered solid solution. On the way to fully disordered state the degree of order either decreases monotonically or goes through a short lived transient state. This behaviour is reminiscent of a first order transition while the equilibrium transition is second order. All the above features are well reproduced by a simple model of driven alloys, which was originally build for alloys under irradiation. The stationary degree of order results of two competitive atomic jump mechanisms: the forced displacements induced by the shearing of the grains, and the thermally activated jumps caused by vacancies migrations. Finally we have performed atomistic simulations with a Monte Carlo kinetic algorithm, which revealed the role of the fluctuations  More>>
Authors:
Publication Date:
Dec 31, 1997
Product Type:
Technical Report
Report Number:
CEA-R-5753
Reference Number:
SCA: 360101; 360102; PA: AIX-29:045500; EDB-98:087542; SN: 98001997335
Resource Relation:
Other Information: DN: 149 refs.; PBD: 1997
Subject:
36 MATERIALS SCIENCE; ALUMINIUM BASE ALLOYS; DISSOLUTION; ELECTRON BEAMS; GERMANIUM BASE ALLOYS; IRON BASE ALLOYS; MICROSTRUCTURE; MILLING; MONTE CARLO METHOD; NICKEL BASE ALLOYS; ORDER-DISORDER TRANSFORMATIONS; PRECIPITATION; VACANCIES
OSTI ID:
636748
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France). Direction des Technologies Avancees.
Country of Origin:
France
Language:
French
Other Identifying Numbers:
Other: ON: DE98633126; TRN: FR9802512045500
Availability:
INIS; OSTI as DE98633126
Submitting Site:
FRN
Size:
197 p.
Announcement Date:

Citation Formats

Pochet, P. Experimental and theoretical study of phase transitions under ball milling; Etude experimentale et modelisation des changements de phases sous broyage a haute energie. France: N. p., 1997. Web.
Pochet, P. Experimental and theoretical study of phase transitions under ball milling; Etude experimentale et modelisation des changements de phases sous broyage a haute energie. France.
Pochet, P. 1997. "Experimental and theoretical study of phase transitions under ball milling; Etude experimentale et modelisation des changements de phases sous broyage a haute energie." France.
@misc{etde_636748,
title = {Experimental and theoretical study of phase transitions under ball milling; Etude experimentale et modelisation des changements de phases sous broyage a haute energie}
author = {Pochet, P}
abstractNote = {The aim of this work was to determine how phase transition s under ball-milling depend on the milling conditions and to find out if one can rationalize such transitions with the theory of driven alloys. We have chosen two phase transitions: the order-disorder transition in Fe Al and the precipitation-dissolution NiGe. In the case of Fe Al we have found that the steady-state long range order parameter achieved under ball milling intensity; moreover the same degree of order is achieved starting from an ordered alloy or a disordered solid solution. On the way to fully disordered state the degree of order either decreases monotonically or goes through a short lived transient state. This behaviour is reminiscent of a first order transition while the equilibrium transition is second order. All the above features are well reproduced by a simple model of driven alloys, which was originally build for alloys under irradiation. The stationary degree of order results of two competitive atomic jump mechanisms: the forced displacements induced by the shearing of the grains, and the thermally activated jumps caused by vacancies migrations. Finally we have performed atomistic simulations with a Monte Carlo kinetic algorithm, which revealed the role of the fluctuations in the intensity of the forcing. Moreover we have shown that specific atomistic mechanisms are active in a dilute NiGe solid solution which might lead to ball milling induced precipitation in under-saturated solid solution. (author). 149 refs.}
place = {France}
year = {1997}
month = {Dec}
}