Superstructure of interstitial ordering of oxygen in TiNi alloys
Journal
Acta Metallurgica
Journal Volume
36
Journal Issue
8
Pages
2065-2070
Date Issued
1988
Author(s)
Abstract
Interstitial ordering of oxygen (resulting in a suboxide) in thin foils of TiNi shape memory alloys induces long-range ordering and "extra" 1 2-reflections. The reciprocal lattice corresponding to these extra reflections can be established from selected area diffraction patterns taken from an identical area. From the tetragonality of the suboxide, oxygen atoms occupy octahedral sites in the TiNi superlattice. By applying the static concentration wave (SCW) method, one can determine the corresponding super-structure of the suboxide, which is a 4 × 2 × 2 superlattice with oxygen-oxygen atom pairs separated by the distance <0 1 2 1 2>a. The stoichiometric formula for the suboxide is Ti16Ni16O4. Using the SCW method, the 1 3-reflections which are also observed are confirmed to be characteristic of the "pre-martensitic" R-phase, and not associated with interstitial ordering. © 1988.
Type
journal article