Abstract
In order to understand the transformation characteristics of Ti Ni shape memory alloys, it is crucial to know its fundamental atomic structure. While many sources have provided detailed explanations about the basic theory of martensitic transformations, it is hard for engineers who do not have expertise in metallurgy to understand the crystal structures because they are illustrated in terms of unit cells in two-dimensional figures. When it comes to lattice correspondence in Bain deformation, which is one of the transformation characteristics, the explanation can be even more complex. Without three-dimensional illustrations of crystal structures, explanations about lattice invariant shear were extremely hard to understand for such engineers. Therefore, changing the viewpoint of conventional ways of the explanation, this paper illustrates a crystal structure in the parent B2 phase as a single unit cell (because Ti and Ni have the same number of atoms) in a method that incorporates Miller indices and Trigonometry projection used in mechanical drawings. This paper also illustrates atomic structures of the parent phases and martensite in three-dimensions to describe the process of martensite transformations (Bain deformation) and two types of atoms in each crystal structure of transformation using different colors.
