Šesták, Černý, Pokluda

Calculated elastic properties of untwinned and twinned B19' martensitic structure of NiTi

Elastic response of twinned and untwinned martensitic structure B19' of NiTi alloy is studied from first principles. An ab initio pseudopotential software package Abinit is used for this purpose. The utilized pseudopotentials with generalized gradient approximation within density functional theory served as a reliable and efficient tool for calculation of energy and stresses.
The simulation cell for twinned martensite in compound twinning mode (100) was composed of eight primitive cells that were adapted to the periodic boundary conditions.
The elastic moduli were computed from uniaxial stress-strain responses near the equilibrium state. The uniaxial strain was applied in several crystallographic directions: <100>, <010>, <001>, and <101>. 
The results obtained revealed that there is no significant difference between the elastic response of the twinned and the untwinned structures. This conclusion is in agreement with available experimental data.