Contributions of Grain Boundary Sliding and Solute Drag Creep to High-Temperature Ductility in Fine-Grained Polycrystalline 5083 Alloys

Abstract:

In this study, the high-temperature ductility of a fine-grained, polycrystalline 5083 solid solution alloy was investigated. The composition of the alloy in mass% was Al–4.5 Mg–0.68 Mn–0.19 Fe–0.13 Si–0.11 Cr. Grain refinement was effectively achieved in the stir zone by a friction stir process, and the grain size could be reduced to 3.7 μm. Tensile tests were performed at temperatures ranging from 643 to 743 K and strain rates ranging from 0.001 to 0.1 /s. The stress–strain curves showed that the flow stress continuously decreased until it reached a maximum value of stress and fractured after the initial strain hardening occurred. The value of elongation-to-failure was more than 100% when temperatures were greater than 693 K. The high ductility observed at this point can be referred to as superplastic-like elongation. This phenomenon has been reported in some Al–Mg alloys. The experimentally determined stress exponent (n value) and activation energy for deformation were about 2.5 and 123 kJ/mol, respectively. These results suggest that the grain boundary sliding, accompanied by solute drag motion of dislocations, was a rate controlling process for deformation.

• Periodical: Advanced Materials Research (Volume 922)
• Pages: 360-365
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.922.360
• Online since: May 2014
• Authors: Takashi Mizuguchi*, Tsutomu Ito, Kota Kimura, Yasuhiro Tanaka
• Keywords: Al-Mg Alloy, Friction Stir Processing (FSP), Grain Boundary Sliding, Solute Drag, Superplastic Deformation

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