Energetics of (1 1 4) twinning in B2 NiTi under coupled shear and shuffle

Tawhid Ezaz, Huseyin Sehitoglu, Hans Jürgen Maier

Research output: Contribution to journalArticlepeer-review

Abstract

The (1 1 4) twin growth in the austenitic regime in NiTi (B2 lattice) is characterized precisely at the atomistic scale. This twinning mode is consistent with experimental observations but has not been well understood despite its importance. Combined shears, shuffles and interface shifts operate in a complex way to generate the (1 1 4) twin. Pure shear on the (1 1 4) plane results in a "pseudo-twin", and interchange shuffles are necessary to convert this to a "reflective" twin and render a lower energy state. Additional atomic shifts at the twin-matrix interfaces result in "sharp" boundaries, further lowering the energy barriers. We established the energy barrier to be 148 mJ m-2 during (114)[221̄] twin boundary growth of four layers at a time. The entire potential energy surface and the mean energy path during twinning can be derived from our simulations, providing the required insight into the atomistic processes involved.

Original languageEnglish (US)
Pages (from-to)339-348
Number of pages10
JournalActa Materialia
Volume60
Issue number1
DOIs
StatePublished - Jan 2012

Keywords

  • (1 1 4) shuffle
  • B2 NiTi
  • Deformation twinning
  • ab initio

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

Fingerprint Dive into the research topics of 'Energetics of (1 1 4) twinning in B2 NiTi under coupled shear and shuffle'. Together they form a unique fingerprint.

Cite this