Even anisotropic superplastic flow, which is a result of an elongated grain shape and texture, can lead to extreme elongations to fracture (superplasticity). Therefore, to identify the mechanisms of deformation present during superplastic flow alone, the effects of the microstructure should be eliminated first. Using an Al 5083 alloy, in which an equi-axed microstructure is present from the beginning, it is shown that grain boundary sliding, accompanied by grain rotations, is the rate controlling mechanism. © (2012) Trans Tech Publications, Switzerland.

S. Sankaran

Department of Metallurgical and Materials Engineering

V. Subramanya Sarma

AL 5083 ALLOYS

EBSD

ELONGATED GRAINS

GRAIN ROTATION

ORIENTATION DISTRIBUTION FUNCTION

Rate-controlling mechanism

RATE-CONTROLLING PROCESS

Steady-state regions

SUPERPLASTIC FLOW

Texture analysis

Distribution functions

Superplasticity

Textures

Grain boundary sliding

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Materials Science Forum

Recent studies have shown that a suitably thermomechanically processed Al-Zn-Mg-Cu-Zr-Sc alloy having an essentially unrecrystallized grain structure may be subjected to superplastic deformation at a temperature and strain rate combination of 475 °C, 1.9 × 10-2 s-1 to obtain a total elongation of 650%. The present work demonstrates that the utilization of two-step strain rate at 425 °C during superplastic deformation of a similarly thermomechanically processed alloy increases the total elongation value to as high as 916%. The beneficial effect of two-step strain rate could further be realized at 350 °C to obtain a total elongation of 438%. Using electron backscattered diffraction, the present work provides a systematic assessment of the changes in (i) percentage recrystallization and (ii) recrystallized grain size with percentage elongation in the material superplastically deformed using both one- and two-step strain rates. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Scripta Materialia

Development of grain structure during superplastic deformation of an Al-Zn-Mg-Cu-Zr alloy containing Sc

Acta Materialia

Diffusion creep and superplasticity in aluminium alloys

Materials Science and Engineering: A

Superplastic behaviour of Al–Zn–Mg–Cu–Zr alloy AA7010 containing Sc

Journal of Materials Science

Texture evolution during deformation of an Al-6%Cu-0.4%Zr superplastic alloy

Grain boundary sliding revisited: Developments in sliding over four decades

Texture analysis for determining the rate controlling process in the transient and steady state regions of superplastic flow

Journal	Materials Science Forum
Publisher	Trans Tech Publications Ltd
ISSN	02555476
Open Access	No