Quantitative Study on the Evolution of Microstructure, Strength, and Electrical Conductivity of the Annealed Oxygen‐Free Copper Wires

Abstract

In the process of electric power transmission, the defects in the copper wire interact with the electrons which results in a thermal effect, accordingly, causing the changes of microstructure and properties of the copper wire. Herein, the evolution of microstructure, strength, and electrical conductivity of the oxygen‐free copper wires annealed at different temperatures is investigated. In addition, the effects of various microstructures on strength and electrical conductivity are quantitatively revealed. In the low‐temperature region (80–150 °C), dislocation recovery is the main reason for the decrease in strength; while, the increase in electrical conductivity is mainly due to the decrease in dislocation density and the transformation of grain boundary from nonequilibrium state to equilibrium state. In the high‐temperature region (above 210 °C), the strength loss is mainly related to the increasing recrystallized grain size and the disappearance of dislocations in the recrystallized region. The increase in electrical conductivity is mainly attributed to the significant decrease in grain boundary density and the further recovery of dislocations.

Erosion behavior and mechanism of Cu-B4C composites under arc discharge in different atmospheres

“…A direct current two-arm bridge was used to measure the electrical resistivity, electrical conductivity (w) can be expressed by the following formula [27]:…”

Evaluation of Mechanical Properties Considering Uncertainties for Hairpin Coils in Electric Vehicle Motor Manufacturing

“…Because this is not a significant concern in conventional motor coils [8], [13], [14], [15], there have been few reports on evaluating the mechanical properties of hairpin coils. Although previous studies have been conducted on the metallurgical effects of copper wires on their mechanical properties, the reliability of the specific test conditions and methods were not addressed in these studies [16], [17], [18], [19], [20], [21]. The mechanical properties of the copper wires in these studies were measured using universal tensile machines (UTMs).…”

Radio-Frequency Conductivity Characteristics and Corresponding Mechanism of Graphene/Copper Multilayer Structures

“…It was found that the sintering temperature and ultrasonic power percentage intensity are the most important parameters affecting the conductivity of sintered samples [ 6 ]. Sun et al developed annealed oxygen-free copper and discovered that the increase in electrical conductivity (~100% IACS) is mainly due to the decrease in dislocation density and the transformation of grain boundaries from a nonequilibrium state to an equilibrium state [ 7 ]. The above studies have achieved encouraging results in exploring copper conductivity; however, achieving conductivity surpassing that of single-crystal Cu remains elusive (~101.5% IACS) [ 8 ].…”