Open Access

ARTICLE

Nucleation and Propagation of Deformation Twin in Polysynthetically Twinned TiAl

by L. G. Zhou¹, L. M. Hsiung², Hanchen Huang¹

1 Department of Mechanical, Aerospace & Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
2 Lawrence Livermore National Laboratory, Chemistry and Materials Science Directorate, P.O. Box 808, L-352, Livermore, CA 94551, USA

Computer Modeling in Engineering & Sciences 2004, 6(3), 245-252. https://doi.org/10.3970/cmes.2004.006.245

Abstract

Using molecular dynamics simulations, we study the deformation of polysynthetically twinned (PST) TiAl at room temperature. The simulation cell is pre-strained and thermodynamically relaxed to zero stress, so that no dislocations pre-exist in γ−α₂ interfaces. A uniaxial compression is then applied along one 1/6<112] direction. Our results show that interfacial dislocation pairs nucleate at the γ−α₂ interface under the compression. The glide and agglomeration of these dislocations lead to the nucleation of deformation twins from the interface. Based on our studies, twins may nucleate without pre-existing interfacial dislocations. Further we have monitored the propagation of the deformation twin, specifically its interaction with γ−γ and γ−α₂ interfaces. The observations show that γ−α₂ interfaces are stronger obstacles to the twin propagation than γ−γ interfaces are.

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Keywords

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