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An Accurate Constitutive Model for AZ31B Magnesium Alloy during Superplastic Forming
Open AccessArticle

Using High-Pressure Torsion to Achieve Superplasticity in an AZ91 Magnesium Alloy

1
Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
2
Materials Research Group, Department of Mechanical Engineering, University of Southampton, Southampton SO17 1BJ, UK
3
Departments of Aerospace and Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453, USA
*
Author to whom correspondence should be addressed.
Metals 2020, 10(5), 681; https://doi.org/10.3390/met10050681
Received: 2 May 2020 / Revised: 13 May 2020 / Accepted: 19 May 2020 / Published: 22 May 2020
(This article belongs to the Special Issue Superplasticity and Superplastic Forming)
An AZ91 magnesium alloy (Mg-9%, Al-1% Zn) was processed by high-pressure torsion (HPT) after solution-heat treatment. Tensile tests were carried out at 423, 523, and 623 K in the strain rate range of 10−5−10−1 s−1 to evaluate the occurrence of superplasticity. Results showed that HPT processing refined the grain structure in the alloy, and grain sizes smaller than 10 µm were retained up to 623 K. Superplastic elongations were observed at low strain rates at 423 K and at all strain rates at 523 K. An examination of the experiment data showed good agreement with the theoretical prediction for grain-boundary sliding, the rate-controlling mechanism for superplasticity. Elongations in the range of 300–400% were observed at 623 K, attributed to a combination of grain-boundary-sliding and dislocation-climb mechanisms. View Full-Text
Keywords: creep; high-pressure torsion; magnesium; superplasticity creep; high-pressure torsion; magnesium; superplasticity
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Figueiredo, R.B.; Langdon, T.G. Using High-Pressure Torsion to Achieve Superplasticity in an AZ91 Magnesium Alloy. Metals 2020, 10, 681.

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