Anisotropy of Electrical Resistivity in Cold Rolled Ti Sheet

Abstract

Observation and evaluation of lattice defects such as vacancy, dislocation and grain boundary are very important for understanding microstructure development during thermo-mechanical treatments. Electrical resistivity measurements are superior to electron microscopies in terms of obtaining average information on micro-and nano-structures including lattice defects. The purpose of this study is to quantify lattice defects and crystallographic features in cold rolled and annealed pure Ti by precise measurements of electrical resistivity. Electrical resistivities at 77 K (liquid nitrogen) and 300 K were measured in a cold rolled Ti sheet at angles of 0, 45, 90°from the rolling direction (RD) by a direct current (DC) four-point method. The resistivity at 90°from RD was slightly higher than that at 0°. A characteristic texture was developed in the sheet; accumulation of (0001) pole was confirmed to appear at an elevation angle of about 40°on the transverse plane. In Matthiessen's empirical relationship for the cold rolled specimens, strong anisotropy in resistivity could also be confirmed. The gradient ¡ and the intercept ¢ values of the relationship might be employed as parameters to quantify the anisotropy of crystal structures and dislocation structures.

The Effect of Interface Morphology on the Electro-Mechanical Properties of Ti/Cu Clad Composites Produced by Explosive Welding

“…[59] This is because in the bonded state, these effects are caused by an increase of lattice defects, such as dislocations, vacancies, and/or grain boundaries, as discussed earlier for deformed Cu [47] and Ti. [60] For example, in copper/ stainless steel clads, [19] an increase in the microhardness near the interface and free surfaces is observed due to cold plastic deformation. Microhardness (strain hardening) increases in the lower part of the base plate due to collisions with the anvil, whereas the microhardness increase in the upper part of the flyer plate is due to the sudden shock of the explosive charge detonation.…”

“…The effect of the <111> and <100> fiber-type texture formation on the electrical resistivity of copper wires has been discussed by Pavithra et al [62] and Moisy [47] and they found no significant effect. On the other hand, Ueda et al [60] showed that the electrical resistivity of cold-rolled cp-Ti is dependent on the formation of specific texture components. They reported that the resistivity along the c-axis of Ti was higher than that along other axes.…”

Measurement of Electrical Resistivity during Tensile Deformation of Pure Ti

“…On the other hand, the resistivity at 300 K, ρ 300 , increased with true strain up to ε t = 0.4, and then decreased before increasing again. This characteristic change in ρ 300 is most likely due to the developed texture 13 . These increases can be attributed to lattice defects introduced by the cold rolling.…”