Deformation processed Al/Ca nano-filamentary composite conductors for HVDC applications

Efficient long-distance power transmission is necessary as the world continues to implement renewable energy sources, often sited in remote areas. Light, strong, high-conductivity materials are desirable for this application to reduce both construction and operational costs. In this study an Al/Ca (11.5% vol.) composite with nano-filamentary reinforcement was produced by powder metallurgy then extruded, swaged, and wire drawn to a maximum true strain of 12.7. The tensile strength increased exponentially as the filament size was reduced to the sub-micron level. In an effort to improve the conductor's ability to operate at elevated temperatures, the deformation-processed wires were heat-treated at 260^°C to transform the Ca-reinforcing filaments to Al₂Ca. Such a transformation raised the tensile strength by as much as 28%, and caused little change in ductility, while the electrical conductivity was reduced by only 1% to 3%. Al/Al₂Ca composites are compared to existing conductor materials to show how implementation could affect installation and performance. (paper)