EFFECT OF MICROALLOYS ON THE MECHANICAL PROPERTIES AND GRAIN GROWTH IN COPPER

摘要

This work examines the effect of microadditions of Zr, Mg, Sn, and Ni on the mechanical properties and grain growth in MOO copper (the total amount of impurities, evaluated from the level of residual electroresistivity r_(4.2), does not exceed 0.002 percent). The alloys were examined in annealed and deformed states. Annealed flat specimens, Z mm thick with grain sizes of 22-40 mm, were tensile tested on an "Instron" tensile testing machine at 20 and 200 deg C, using extensometers. The error in determining sigma_u, sigma_(0.2), and sigma_(0.005), was 5 percent. A feature of the concentration relationships for the yield point of binary alloys is the nonmonotous character which is manifested by a drop in the strength properties (the behavior of sigma_u, sigma_(0.2), and s_(0.005) was analogous) at a concentration of 0.01 percent (Fig. 1). The concentration relationship of the modulus for the normal elasticity of copper alloys with Zr (with the latter content at about 0.01 percent)~1 shows a reduction in the modulus. At this concentration of Zr, Mg, and Sn in binary copper alloys a reduction was noted in the recrystallization temperature for copper which, judging from r_(4.2), had not combined with the refined copper. These effects have still not received sufficiently convincing explanation.