The Mechanisms Of Rare Earth La,Ce On Pure Copper And High Strength And High Copper Alloys

In this dissertation, the main focus is on the inner mechanism of elements added in pure copper—chromium, rare earth lanthanum and cerium , combined as the same time either with chromium and lanthanum or with chromium and cerium —and their influence on casting microstructure, conductivity and mechanical properties. It has been found out that most of the added elements spreads over the grain interfaces. The findings also show that the relatively smaller quantity of added lanthanum and chromium (0.02%La, 0.2%Cr) exist in an irregular form in the pure copper; while larger quantity of them (with 0.08%La, 0.8%Cr) are mainly in the form of Cr2La. In addition, the sample's resistivity of chromium and cerium added simultaneously into pure copper is lower than that of pure copper or that of only one of the above two elements added in pure copper, but the strength and hardness of the former are higher than those of the latter two. In the condition of this experiment, for the sake of best combination of high strength and high conductivity, the best proportion of added elements of chromium in the alloy of Cu-Cr-La is 0.4%, that of La 0.02%, while in the alloy of Cu-Cr-Ce, the perfect added proportion of Cr is 0.8% and Ce 0.08%.