MATHEMATICAL MODELLING OF DECORATION PEAK ASSOCIATED WITH DRAGGING POINT DEFECTS SITUATED SELECTIVELY AT THE KINK CHAIN WITH SPECIAL REFERENCES TO HYDROGENATED BCC AND FCC METALS

Tarik O. OGURTANI
Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara 06531, Turkey

The set of nonlinear differential equations that describes the kink chain oscillating in an atmosphere of continuously distributed paraelastic or isotropic point defects and, in addition, decorated by a dragging point defect at the midpoint, is solved numerically after introducing a novel scaling and renormalization procedure. The internal friction coefficient obtained indicates the existence of two separate peaks, the decoration peak and the parent peak, which are directly related to the localized point defect dragging and the smeared-out paraelastic or isotropic defect atmospheres, respectively. It is also shown by extensive experimental data analysis that this decoration theory, collaborating with the nonlinear theory of kink viscosity, results in an extremely accurate prediction of the effective activation enthalpy of dislocation relaxations, especially in the case of hydrogen (isotropic) Snoek-Koster peaks in plastically deformed bcc and fee metals.