Contribution of phase and structural transformations to linear and nonlinear mechanisms of anelasticity in binary Al-Mg alloys

• Published in: Physics of metals and metallography Vol. 115; no. 1; pp. 77 - 84
• Main Authors: Golovin, I. S., Bychkov, A. S., Golovin, S. A.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 2014; Springer; Springer Nature B.V
• Subjects: Alloys; Aluminum base alloys; Amplitudes; Analysis; Chemistry and Materials Science; Degassing of metals; Dislocations; Internal friction; Magnesium; Magnesium base alloys; Materials Science; Metallic Materials; Metals; Rain and rainfall; Recrystallization; Specialty metals industry; Strength and Plasticity; β phase; relaxation and hysteresis mechanisms of anelasticity; Al-Mg alloys
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X14010062

Effects of the processes of the recrystallization and precipitation of the β phase in Al-(0.3–12%)% Mg alloys on the mechanisms of grain-boundary relaxation and dislocation-induced microplasticity have been studied in some detail. The decrease in the dislocation density due to the process of recrystallization of cold-worked alloys leads to the formation of a pseudopeak in the curves of the temperature dependence of internal friction and to a decrease in the critical amplitude of deformation necessary to initiate dislocation motion in a stress field. The precipitation of the β phase in the structure suppresses the mechanism of grain-boundary relaxation; the dissolution of the β phase, which leads to the formation of impurity atmospheres, then to the passage of magnesium atoms into the solid solution, impedes dislocation motion. Depending on the total content of Mg in the alloy, the dislocation mobility upon the measurements of amplitude dependences of internal friction can be described in terms of either breakaway or friction models. The characteristics of grain-boundary relaxation and dislocation-impurity interaction and of their temperature dependences have been estimated quantitatively.