Influence of Microadditions of Yttrium on the Structure, Mechanical Properties, and Conductivity of Copper

We show that microadditions of yttrium significantly change the fine structure and properties of copper obtained by vacuum melting. In addition to the phases inherent in copper, there appear phases up to 20 nm in size, the number of precipitations of which increases with increase in the yttrium content. The solidus temperature of copper containing more than 0.04% of yttrium is equal to (860 ± 5)°C. For copper containing 0.03, 0.02, 0.01, and 0.005% of yttrium, the temperature is equal to 920, 1000, 1040, and 1057°C, respectively. The comparative analysis of the temperature dependence of the mechanical characteristics of strips of cathodic copper, vacuum inductive copper, vacuum electron-beam copper, and copper microalloyed with yttrium containing 0.01-0.03% of yttrium shows that, in the temperature range 20-600°C, copper microalloyed with yttrium has the best characteristics. Alloying of copper in the process of vacuum remelting with small additions of yttrium (0.01-0.02%) leads to both stabilization of copper and an increase in its conductivity as compared with the unalloyed copper obtained by vacuum melting.