Analysis of the Cu-3 Wt pct Ti cellular interphase boundary by various models

Abstract

The cellular-interlamellar interface in Cu-3 wt pct Ti is modeled employing three different theoretical approaches, which are then compared to experimental observations obtained by transmission electron strain contrast and high-resolution microscopy. The simplest modeling technique used is interfacial superposition, which is shown to give useful information on the general nature of the interface. Van der Merwe’s ideal interfacial-configuration model, which calculates the relative energies of different misorientations and dilatations, establishes three nearby energy minima over azimuthal rotations of less than 1 deg for a given interlamellar habit plane. This is too small a rotation to differentiate by experiment alone. From this ideal interfacial-configuration model, a different orientation relationship than previously reported in the literature is proposed that more closely represents the experimental observations when combined with O-lattice calculations, viz., (111) _α ‖ (010) _β with [-101] _α ‖ [501] _β , where α is the fcc matrix, and β is the Cu₄Ti orthorhombic phase. Probable defect networks were determined by the O-lattice method for the new and previously proposed orientation relationships (ORs).