抄録
Cu–Zr–Cr alloy does not soften by prolonged high-temperature heating and its electrical conductivity ranges between 75 and 80% IACS, so that the alloy is extensively used as electrodes for diverse welding purposes.
A study of the origin of high softening temperature in this alloy has been made using a transmission electron microscope. The results show that the presence of Cr and Zr atoms in copper solid solution retard the recovery, recrystallization and precipitation. The recovery and recrystallization, which result from the dislocation climb and glide, may be retarded by : (1) the apparent locking of dislocations due to the presence of Cr or Zr atoms or both, and (2) the reduction in self-diffusivity of the Cu in copper solid solution due to the presence of Cr or Zr, or both. From the retardation of recovery and recrystallization in the ternary alloy, it can also be predicted that the diffusion coefficient of Cr or Zr, or both, is low.
Aging at 400°C for 1 hr after roll-flattening hardens the Cu–Zr–Cr alloy. However, transmission electron microscopy does not reveal the origin of the hardening. This may correspond to the phenomena known as “low temperature anneal hardening”.
