Molecular Dynamics Simulation and Crystal Variant Identification of Shape Memory Alloys
Date Issued
2015
Date
2015
Author(s)
Wu, Jo-Fan
Abstract
Shape memory alloys (SMAs) behave interesting and important mechanical properties due to the solid-solid phase transformation. These phenomena are dominated by the evolution of microstructures. In recent years, the microstructures in SMAs have been studied extensively and modeled using molecular dynamics (MD) simulations. However, it remains challenging to identify the crystal variants in the simulation results which consist of large amount of atoms. In the present work, a method is developed to identify the austenite parent phase and the monoclinic martensite crystal variants from MD results. The transformation matrix of the lattices is calculated to determine the corresponding crystal variants. Evolution of the volume fraction of the crystal variants and the microstructure in the Ni-Ti SMAs under thermal cycling induced phase transition are examined. The method is validated by comparing several interface normal observed from MD results with the theoretical solutions via the compatibility equation.
Subjects
Ni-Ti shape memory alloys
Microstructure
Phase transition
Molecular dynamics
Type
thesis
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