Simulation Studies on Phase Transformations in Binary Shape Memory Alloys

In recent years, simulation studies in material science have been increasing. The molecular dynamics simulation is the most popular one, taking into account the dynamic behaviour of atoms concerned with the modelled system. In this simulation method, the relevant systems have been modelled by suitable potential energy functions defining the interatomic interactions between atoms. Therefore, the success of the simulation belongs to the potential energy functions. These functions can be established on pair-wise or many-body interaction concepts, depending on where to use. The pair-wise interaction models such as Lennard-Jones or Morse functions do not support the Cauchy pressure (C12-C44) in many metallic systems. Therefore, in our simulation studies on binary NiAl shape memory alloys, Voter-Chen embedded atom method based on many-body interaction concepts have been employed. In the simulations, Parrinello-Rahman molecular dynamics method and fifth order predictor-corrector algorithm to integrate the equations of motion of the model systems with different number of atoms, in the range of 1024 to 16000, have been adopted. It has been observed that the alloy models exhibit thermoelastic phase transformation and the transition temperatures change depending on the number of atoms in the model system

Keywords:

Molecular dynamics simulation , embedded atom method , NiAl , shape memory alloys