Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg

Donya Ahmadkhaniha; Yi Huang; Matias Jaskari; Antti Järvenpää; Mahmoud Heydarzadeh Sohi; Caterina Zanella; L Pentti Karjalainen; Terence G Langdon

doi:10.1007/s10853-018-2779-1

Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg

J Mater Sci. 2018;53(24):16585-16597. doi: 10.1007/s10853-018-2779-1. Epub 2018 Aug 13.

Authors

Donya Ahmadkhaniha¹, Yi Huang^{2

3}, Matias Jaskari⁴, Antti Järvenpää⁴, Mahmoud Heydarzadeh Sohi⁵, Caterina Zanella¹, L Pentti Karjalainen⁶, Terence G Langdon²

Affiliations

¹ 1Department of Material and Manufacturing, School of Engineering, Jönköping University, P.O. Box 1026, Gjuterigatan 5, SE-551 11 Jönköping, Sweden.
² 2Materials Research Group, Department of Mechanical Engineering, University of Southampton, Southampton, SO17 1BJ UK.
³ 3Department of Design and Engineering, Faculty of Science and Technology, Bournemouth University, Poole, Dorset BH12 5BB UK.
⁴ 4Kerttu Saalasti Institute, University of Oulu, Pajatie 5, 85500 Nivala, Finland.
⁵ 5School of Metallurgy and Materials, College of Engineering, University of Tehran, PO Box 1155-4563, Tehran, Iran.
⁶ 6Centre for Advanced Steels Research, University of Oulu, PO Box 4200, 90014 Oulu, Finland.

Abstract

High-pressure torsion (HPT) processing was applied to cast pure magnesium, and the effects of the deformation on the microstructure, hardness, tensile properties and corrosion resistance were evaluated. The microstructures of the processed samples were examined by electron backscatter diffraction, and the mechanical properties were determined by Vickers hardness and tensile testing. The corrosion resistance was studied using electrochemical impedance spectroscopy in a 3.5% NaCl solution. The results show that HPT processing effectively refines the grain size of Mg from millimeters in the cast structure to a few micrometers after processing and also creates a basal texture on the surface. It was found that one or five turns of HPT produced no significant difference in the grain size of the processed Mg and the hardness was a maximum after one turn due to recovery in some grains. Measurements showed that the yield strength of the cast Mg increased by about seven times whereas the corrosion resistance was not significantly affected by the HPT processing.