Internal Friction and Dynamic Modulus of Cold-Worked Metals

The complexities of the internal friction and dynamic modulus of metals in the cold-worked condition may be understood reasonably well by separation of the phenomena into the following three distinct effects: (1) the ``nonlinear'' effect, characterized by strong amplitude dependence, frequency independence, and its disappearance after severe deformation; (2) the Köster effect, which shows rapid recovery after deformation, at temperatures well below the recrystallization temperature; (3) the ``viscosity'' effect, characterized by strong frequency and temperature dependence. The origin of each of these effects is briefly discussed from the point of view of dislocation theory.