Influence of Minor Aluminum Addition on the Superplastic Deformation of a Microduplex Cu-Zn Alloy

• Published in: Physical mesomechanics Vol. 26; no. 5; pp. 533 - 541
• Main Authors: Yakovtseva, O. A., Kaboyi, P. K., Irzhak, A. V., Mikhaylovskaya, A. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.10.2023; Springer Nature B.V
• Subjects: Alloying; Aluminum; Brasses; Classical Mechanics; Copper base alloys; Copper zinc alloys; Deformation; Dynamic recrystallization; Elongation; Grain boundaries; Grain boundary sliding; Grain size; Materials Science; Mechanical properties; Physics; Physics and Astronomy; Porosity; Room temperature; Solid State Physics; Strain localization; Superplastic deformation; Superplasticity; Ultrafines; Yield strength; grain boundary sliding; intragranular dislocation slip; diffusion; brass; superplastic deformation mechanisms
• ISSN: 1029-9599; 1990-5424
• DOI: 10.1134/S1029959923050065

High residual porosity in superplastically deformed brass carries the risk of reducing the mechanical properties. Multicomponent brasses demonstrate lower residual porosity, associated with a lower grain size and more effective accommodation of grain boundary sliding. In this paper, the microstructural evolution of the surface and bulk structure of the binary brass and aluminum-bearing brass during steady-state superplastic deformation is compared. After superplastic deformation, dislocation pile-ups and dislocation walls are revealed in the α grains of both alloys, indicating the activation of the dislocation slip/creep mechanism. It is shown that aluminum reduces the contribution of grain boundary sliding along the phase boundaries from ~75 to ~30% and causes strain localization in the β-phase region with the formation of ultrafine grains with the size below ~300 nm as a result of dynamic recrystallization. Alloying with 0.4% Al reduces the flow stress by 20%, increases the relative elongation by a factor of 1.5, and decreases the fraction of residual porosity by a factor of 3. This leads to a much lower loss of room temperature strength in superplastically deformed alloys.