On deformation twinning in b. c. c. metals
- Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering
A new model of deformation twinning in b.c.c. metals based on the dissociation of an a/2(111) screw dislocations into three co-linear a/6(111) partials on three adjacent (11[bar 2]) planes is proposed. A short screw segment of this zonal dislocation bows out under an applied stress in a fashion similar to a Frank-Read source, where each of the three partials glides on its individuals (11[bar 2]) plane. The correlated motion of the three partials on three adjacent (11[bar 2]) planes forms a three layered micro-twin. After one Frank-Read zonal dislocation loop forms, the screw segment undergoes cross-slip in a similar fashion as the model proposed by Pirouz for twinning in Si because the formation of a second Frank-Reid zonal dislocation loop would produce a stacking sequence of (11[bar 2]) planes associated with a high energy stacking fault. However, after cross-slip the screw-segment may again bow out on a new set of parallel (11[bar 2]) planes to form another three layered micro-twin bound by the zonal dislocation loop. The repeated cross-slip and bowing out of such zonal dislocation loops results in both lateral growth and thickening of the deformation twin.
- OSTI ID:
- 6327894
- Journal Information:
- Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 41:7; ISSN 0956-7151; ISSN AMATEB
- Country of Publication:
- United States
- Language:
- English
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