Publication Date

10-12-2020

Department

Ames Laboratory

Campus Units

Ames Laboratory

OSTI ID+

1671758

Report Number

IS-J 10317

DOI

10.1103/PhysRevMaterials.4.103606

Journal Title

Physical Review Materials

Volume Number

4

Issue Number

10

First Page

103606

Abstract

We use ab initio calculations to study the role of stacking faults in connecting the high-temperature B2 and the theoretically predicted low-temperature B33 NiTi phases. In contrast with prior work, we describe the B2 -> B33 phase transformation in terms of alternate bilayer shifts by 1/2[100] on the (011)(B2) plane, obtaining a viable pathway; the same mechanism could also work with the B19 parent phase. We then examine B33-like structures built from alternate stacking sequences of B19 bilayers, constructed to have monoclinic tilt angles close to the experimentally reported NiTi B19' martensite, and find four low-energy stacking-fault variants with energies 5.8-8.5 meV/atom above the calculated B19' martensite structure, suggesting that such structures might appear as a part of the NiTi martensite phase at low temperatures. Investigating further the occurrence of specific coordinated planar shifts in NiTi systems, we report a dynamically stable NiTi B27 phase and find that it is only 1.2 meV/atom above the calculated B33 ground-state structure, thus having a potential to also play a role in NiTi martensitic phase transformation.

DOE Contract Number(s)

AC02-07CH11358; AC05-00OR22725

Language

en

Department of Energy Subject Categories

36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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