THE STUDY OF INTERNAL-FRICTION IN METAL-METAL LAYERED MATERIALS

Internal-friction and modulus measurements were made on 99.999% pure A l samples of stabilized grain structure and on the samples covered by a Cu or Zn layer produced by electrodeposition. These layered samples were heat treated in order to cause diffusion of the foreign atoms int o the Al mainly along the grain boundaries. The usual grain boundary r elaxation was decreased or suppressed by the foreign atoms but the Cu turned out to be more effective in this sense. For sufficiently thick Zn layers, even a new relaxational peak appeared. The essential role o f the grain boundary dislocations can be concluded from the unusual is othermal results observed in the grain boundary relaxation temperature range, and from the amplitude dependence of the layered samples after heat treatment. The role of the covering Zn or Cu layer in the dynami c recrystallization under axial stress was also investigated.