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Mesoscale kinetics produces martensitic microstructure

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Original languageEnglish
Pages (from-to)109-121
Number of pages13
JournalJournal of the mechanics and physics of solids
Volume57
Issue number1
DOIs
StatePublished - Jan 2009

Abstract

We present molecular dynamics (MD) simulations of a martensitic phase transformation studying post-transformation microstructure and moving austenite-martensite interfaces. Unlike in energy-minimisation theories, the transformation dynamics dominate the martensite morphology. We use a binary Lennard-Jones potential to describe a square-to-hexagonal transformation by shear-and-shuffle. The high-T stable square lattice and low-T hexagonal lattice represent austenite and martensite, giving four martensitic variants. Compatible twin variants have no lattice misfit and zero interfacial energies which makes our model directly comparable with the crystallographic theory of martensite. Although our dynamical interpretation is different to previous work, our MID simulations exhibit very similar martensitic morphologies to real materials. We observe the nucleation of wedge-shaped, twinned martensite plates, plate growth at narrow, travelling transformation zones, subsonic transformation waves, elastic precursors inducing secondary nucleations and the formation of martensitic domains. Martensite is produced within narrow transformation zones where atoms change their lattice sites in a co-operative manner so as to form crystallographic layers. These motions produce inertia forces on the mesoscopic length-scale which induce the formation of twin variants in the Subsequent layers to transform. (C) 2008 Elsevier Ltd. All rights reserved.

    Research areas

  • Martensitic transformation, Molecular dynamics, Microstructure, Transformation dynamics, Twinning, MOLECULAR-DYNAMICS SIMULATIONS, PHASE-TRANSITIONS, 2D MODEL, NI-AL, TRANSFORMATIONS, ALLOYS, ENERGY, SYSTEM

ID: 1277623