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In situ transmission electron microscopy investigation on 〈c + a〉 slip in Mg

  • Dalong Zhang (a1), Lin Jiang (a1), Xin Wang (a1), Irene J. Beyerlein (a2), Andrew M. Minor (a3), Julie M. Schoenung (a1), Subhash Mahajan (a4) and Enrique J. Lavernia (a1)...

Abstract

Recent molecular dynamics simulations revealed that 〈c + a〉 dislocations in Mg were prone to dissociation on the basal plane, thus becoming sessile. Basal dissociation of 〈c + a〉 dislocations is significant because it is a major factor in the limited ductility and high work-hardening in Mg. We report an in situ transmission electron microscopy study of the deformation process using an H-bar-shaped thin foil of Mg single crystal designed to facilitate 〈c + a〉 slip, observe 〈c + a〉 dislocation activity, and establish the validity of the largely immobile 〈c + a〉 dislocations caused by the predicted basal dissociation. In addition, through detailed observations on the fine movement of some 〈c + a〉 dislocations, it was revealed that limited bowing out movement for some non-basal portions of 〈c + a〉 dislocations was possible; under certain circumstances, i.e., through attraction and reaction between two 〈c + a〉 dislocations on the same pyramidal plane, at least portions of the sessile configuration were observed to be reversed into a glissile one.

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a)Address all correspondence to this author. e-mail: lavernia@uci.edu

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b)

Now at Pacific Northwest National Laboratory.

c)

Now at Materials & Structural Analysis, Thermo Fisher Scientific, Hillsboro, OR, 97124.

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