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Sensitivity of deformation twinning to grain size in titanium and magnesium

journal contribution
posted on 2011-12-01, 00:00 authored by Alireza Ghaderi, Matthew BarnettMatthew Barnett
The impact of grain size on deformation twinning in commercial purity titanium and magnesium alloy Mg–3Al–1Zn (AZ31) is investigated. Tensile tests were carried out for the titanium samples; compression testing was employed for the magnesium specimens. Average values of the true twin length, true twin thickness and the number density of twins were determined using stereology. A key difference between these two materials is that twinning contributes little to the plastic strain in the titanium while it accounts for nearly all of the early plastic strain in the magnesium. In some respects (e.g. volume fraction and number density) the phenomenology of twinning differed between the two materials, while in others (e.g. twin shape and size) both materials showed a similar response. It is found that in both materials, twins span the entirety of their parent grains only for grain sizes less than ∼30 μm. Both the nucleation density per unit of nucleating interface (i.e. grain and twin boundaries) and the aspect ratio of twins scale with applied stress. The impact of grain size on twin volume fraction is modelled analytically.

History

Journal

Acta materialia

Volume

59

Issue

20

Pagination

7824 - 7839

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

1359-6454

eISSN

1873-2453

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2011, Elsevier