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Microstructural properties, thermal stability and superplasticity of a ZK60 Mg alloy processed by high-pressure torsion

Microstructural properties, thermal stability and superplasticity of a ZK60 Mg alloy processed by high-pressure torsion
Microstructural properties, thermal stability and superplasticity of a ZK60 Mg alloy processed by high-pressure torsion
An extruded ZK60 magnesium alloy was used to investigate microstructure, hardness and tensile properties after processing by 5 turns of high-pressure torsion (HPT) at room temperature. EBSD results confirmed the successful production of an ultrafine-grained structure with a mean grain size of ~700 nm with reasonable homogeneity and a majority of grains oriented parallel to the shear direction. This material also reached a homogeneous microhardness across the disk with an average hardness value saturated at Hv ?124 from the as-received hardness value of Hv ?74. The obtained high value is due to a high density of dislocations, the very small grain size and texture strengthening. The microhardness retained homogeneity after annealing samples processed by HPT for 40 hours at 448 K. However, the hardness value dropped to Hv ?85 while the mean grain size increased to ~2.1 ?m. These changes may be a result of restoration processes and consequent texture softening. Specimens processed by 5 turns of HPT exhibit excellent superplastic properties with a maximum elongation of 940% at 523 K and an optimum strain rate of 1.0×10-4 s-1. Significant superplasticity was observed at 448 K due to the stability of the bimodal structure at lower temperatures. This can assist the microstructure to accommodate grain boundary sliding and intragranular slip simultaneously and postpone any necking.
2218-5046
287-293
Torbati-Sarraf, S.A.
d955718a-1375-448e-a022-55861ecf4852
Sabbaghianrad, S.
a061a940-ba10-4c18-945c-142464addb36
Langdon, T.G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Torbati-Sarraf, S.A.
d955718a-1375-448e-a022-55861ecf4852
Sabbaghianrad, S.
a061a940-ba10-4c18-945c-142464addb36
Langdon, T.G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86

Torbati-Sarraf, S.A., Sabbaghianrad, S. and Langdon, T.G. (2015) Microstructural properties, thermal stability and superplasticity of a ZK60 Mg alloy processed by high-pressure torsion. Letters on Materials, 53 (3), 287-293.

Record type: Article

Abstract

An extruded ZK60 magnesium alloy was used to investigate microstructure, hardness and tensile properties after processing by 5 turns of high-pressure torsion (HPT) at room temperature. EBSD results confirmed the successful production of an ultrafine-grained structure with a mean grain size of ~700 nm with reasonable homogeneity and a majority of grains oriented parallel to the shear direction. This material also reached a homogeneous microhardness across the disk with an average hardness value saturated at Hv ?124 from the as-received hardness value of Hv ?74. The obtained high value is due to a high density of dislocations, the very small grain size and texture strengthening. The microhardness retained homogeneity after annealing samples processed by HPT for 40 hours at 448 K. However, the hardness value dropped to Hv ?85 while the mean grain size increased to ~2.1 ?m. These changes may be a result of restoration processes and consequent texture softening. Specimens processed by 5 turns of HPT exhibit excellent superplastic properties with a maximum elongation of 940% at 523 K and an optimum strain rate of 1.0×10-4 s-1. Significant superplasticity was observed at 448 K due to the stability of the bimodal structure at lower temperatures. This can assist the microstructure to accommodate grain boundary sliding and intragranular slip simultaneously and postpone any necking.

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More information

Accepted/In Press date: 30 January 2015
Published date: 2015
Organisations: Engineering Mats & Surface Engineerg Gp

Identifiers

Local EPrints ID: 382401
URI: http://eprints.soton.ac.uk/id/eprint/382401
ISSN: 2218-5046
PURE UUID: 83b54f94-a82e-4f71-a9b2-11087ad8cbcc
ORCID for T.G. Langdon: ORCID iD orcid.org/0000-0003-3541-9250

Catalogue record

Date deposited: 27 Oct 2015 12:00
Last modified: 12 Dec 2021 03:19

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Contributors

Author: S.A. Torbati-Sarraf
Author: S. Sabbaghianrad
Author: T.G. Langdon ORCID iD

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