Application of the CSL model to deformation twin boundary in B2 Type TiNi compound

Minoru Nishida, Mituhiro Matsuda, Yasuhiro Morizono, Towako Fujimoto, Hideharu Nakashima

Research output: Contribution to journalArticle

Abstract

The deformation structure of B2 type TiNi compound around 573 K has been investigated by transmission electron microscopy (TEM). Serrations are seen in stress-strain curve, which corresponds to the formation of various planar defects with twin relation. The dominant planar defect found in the specimens showing serration is {114} compound twin. The other defects are in mirror symmetry with respect to {113}, {115}, {447} planes and so on. These defects are considered to be 〈110〉 symmetric tilt boundaries in bcc structure by ignoring the atomic arrangement of B2 structure and are characterized with ∑ value based on coincide site lattice (CSL) model. For instance, the ∑ value of {114}, {113}, {115} and {447} boundaries are ∑9, ∑11, ∑27 and ∑81, respectively. Numerous (114) defects initially form at grain boundary and grow into grain interior, Some of those deflect to (-1-14) defects. In such case, the {447} ∑81defect is always observed at the interface of (114) ∑9 and (-1-14) ∑9 defects. This fact indicates that the sigma combination rule of the CSL model can be applied to the triple junction of defects. Similarly, {7710} ∑99 boundary forms at the interface of {114} ∑9 and {113} ∑11 defects. It can be concluded that the ductility of B2 type TiNi compound around 573 K is attributable to the formation of various planar defects with large shear strain and the increment of independent slip system due to the formation of planar defects, and that the arrangement of some planar defects conforms to the sigma combination rule of CSL model.

Original languageEnglish
Article numberS5.2
Pages (from-to)371-376
Number of pages6
JournalUnknown Journal
Volume842
Publication statusPublished - 2005

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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