Internal friction caused by migration of the intercrystalline boundary in the metal

Abstract

The model of internal friction at the migrating intercrystalline boundary is considered. Under the action of an alternating external stress oriented normally to the boundary, compression and stretching of the mating crystallites occurs. Due to their anisotropy and mutual reversal, Young’s modules in the direction of the stress action are different. The volume density of elastic energy in crystallites is different. This leads to the emergence of an effective driving force for boundary migration. As a model, a square segment of the boundary is selected, fixed along the perimeter by triple grain joints. The Laplace stress from the side of the curved boundary is counteracting. The differential equation of the connection of the boundary displacement with the total voltage is solved by the Fourier method. Based on this solution, the internal friction is calculated. The relaxation time spectrum consists of a series of lines. Each of them corresponds to the peak of Debye. The main peak has a significant value, smaller peaks are superimposed on it. The resulting maximum of internal friction widens in comparison with the Debye peak.

Keywords

• driving force
• migration of the intercrystalline boundary
• peak of internal friction
• relaxation time