Incubation times and entropy barriers in martensitic kinetics: Monte Carlo quench simulations of strain pseudospins
Martensitic materials quenched from the austenite phase can show hugely different conversion kinetics: explosively rapid (“athermal”), or slowly incubated (“isothermal”). This traditional sharp distinction was queried by experiments finding conversion-incubation delay tails even in athermal martensi...
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Published in | Europhysics letters Vol. 92; no. 3; pp. 36002 - 36007 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
IOP Publishing
01.11.2010
EPS, SIF, EDP Sciences and IOP Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | Martensitic materials quenched from the austenite phase can show hugely different conversion kinetics: explosively rapid (“athermal”), or slowly incubated (“isothermal”). This traditional sharp distinction was queried by experiments finding conversion-incubation delay tails even in athermal martensites, at temperatures where only austenite should exist. To understand martensitic kinetics, we perform systematic Monte Carlo temperature-quench simulations of a protoypical martensitic model of S=0, ±1 strain pseudospins, with compatibility-induced, power law anisotropic interactions, and no extrinsic disorder. We find both athermal or isothermal behaviour in the same model, depending on parameters. In the athermal regime, the puzzling experimental temperature-time behaviour for conversions is reproduced: explosive conversions (below a spinodal), do indeed coexist with rising incubation-delay tails. A Vogel-Fulcher divergence at transition is predicted, in a region of tweed-like precursors. Incubations are explained as searches for rare, finite-scale transitional states, that are explicitly identified. Although complex textural changes occur during incubation, the energies are quite flat, in a signature of entropy barriers. The model suggests systematic quench experiments in martensites. |
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Bibliography: | ark:/67375/80W-0PV586MQ-K publisher-ID:epl13079 istex:C5C7F7E645A3BD894CB9A367BA56C3A51BD137AC ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0295-5075 1286-4854 |
DOI: | 10.1209/0295-5075/92/36002 |