Direct Comparison of Molecular Dynamics Models for Superelasticity in NiTi

Abstract Shape memory alloys (SMAs) are known for their ability to revert to their original shape upon unloading, exhibiting what is known as superelasticity behavior. Traditional continuum-based constitutive models rely heavily on a large number of tests to reproduce the superelasticity response. Recent studies on NiTi SMAs using molecular dynamics (MD) and the ab-initio approach based on density functional theory (DFT) have examined their behavior without the need for extensive experimental efforts. However, in presenting the MD-based models, previous work was limited to demonstrating only a few cases where the simulation was satisfactory. However, when a large number of scenarios are considered, the limitations become clear. In this work, several interatomic potentials in MD are utilized to study a wide range of conditions in NiTi SMAs. These scenarios include predicting transformation stress, tension–compression asymmetry, stress hysteresis, Clausius-Clapeyron curves, elastic moduli, recoverable strains, martensite crystal phase details, and temperature changes during the transformation. The work highlights the advantages and limitations of the MD potential models, providing a critical assessment. This paper honors the memory of Prof. Franco Furgiuele, University of Calabria. It was a privilege to be his friend and colleague. His sudden passing in summer 2024 was a profound loss for our community. He will be forever remembered for his cherished memories and profound insights into mechanical engineering (written by Prof. Sehitoglu).