Deformation Twinning in Ni₂MnGa

Authors

R. C. Pond, University of Exeter
Brittany Muntifering, Boise State University
Peter Müllner, Boise State UniversityFollow

Document Type

Article

Publication Date

5-1-2012

Abstract

Deformation twinning is investigated in the martensitic phase of a Ni_46.75Mn₃₄Ga_19.25 (at.%) alloy. X-ray and electron diffraction are used to establish the crystallography of the non-modulated tetragonal martensite, and transmission electron microscopy is employed to deduce the twinning parameters. It is convenient to define the twinning parameters with respect to a "monoclinic" unit cell, designated 2M: then K₁, η₁, K₂, and η₂ are (0 0 1), [1 0 0], (1 0 0), and [0 0 1] respectively. The Burgers vector of the active twinning disconnections is close to 1/6[1 0 0] and the disconnections are associated with steps of height d₍₀₀₂₎. These defects are expected to be highly mobile since their motion does not require atomic shuffling. It is shown that periodic arrangements of two layer twins produce modulated crystal structures, such as 14M.

Publication Information

Pond, R. C.; Muntifering, Brittany; and Müllner, Peter. (2012). "Deformation Twinning in Ni₂MnGa". Acta Materialia, 60(9), 3976-3984. https://doi.org/10.1016/j.actamat.2012.03.045