Mechanisms of Superplastic High-Rate Deformation in the Al–Mg–Zn–Fe–Ni–Zr–Sc Alloy

• Published in: Physics of metals and metallography Vol. 120; no. 10; pp. 1014 - 1020
• Main Authors: Yakovtseva, O. A., Kotov, A. D., Sitkina, M. N., Irzhak, A. V., Mikhaylovskaya, A. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.10.2019; Springer Nature B.V
• Subjects: Aluminum; Chemistry and Materials Science; Creep (materials); Deformation mechanisms; Elongation; Ferrous alloys; Grain boundary sliding; Ion etching; Iron; Magnesium; Materials Science; Metallic Materials; Microstructure; Nickel; Plastic deformation; Scandium; Strain rate; Strength and Plasticity; Superplastic deformation; Superplastic forming; Superplasticity; True strain; Zinc; Zirconium; grain boundary sliding; dislocation structure; superplasticity; diffusional creep; aluminum alloys
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X19100156

The microstructure and acting superplastic deformation mechanisms in the high-strength Al–7.0% Zn–2.7% Mg–1.0% Ni–0.9% Fe alloy low-doped with Sc and Zr upon deformation at a temperature of 480°С and a strain rate of 1 × 10 –2 s –1 at a stable flow stage in a true strain range of 1.1 to 1.6 have been investigated. To evaluate the contributions of superplastic deformation mechanisms to the total elongation, marker grids have been applied on the surface by ion etching, and microstructural changes of the surface have been analyzed. Grain boundary sliding and intragranular deformation play dominant roles. The contribution of each mechanism is 35–40%. The remaining 25% belongs to the diffusional creep mechanism, which is determined from the size of striated zones formed at the transverse grain boundaries on the surface of a deformed sample.