MAGNESIUM STRUCTURE AND TEXTURE AFTER THE LOW-TEMPERATURE MEGAPLASTIC DEFORMATION


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Abstract

Magnesium and its alloys belong to the lightest metal structural materials. However, at the moment, the application of magnesium alloys is limited due to their poor workability and low ductility at low temperatures that is caused by the crystalline structure of magnesium and the limited number of active slip systems. The mechanical properties of the material can be improved significantly by means of creation of the fine-grained structure using the megaplastic deformation methods.

The authors used the scanning electron microscopy method, EBSD-analysis and tensile tests to study the structure, texture and mechanical properties of 1-mm magnesium plates and 120-μm magnesium foils produced in the result of megaplastic deformation using the transverse extrusion method (the first stage) and further rolling (the second stage) at room temperature and at the temperature of about −100°C. Total true strain after two stages was e~6.0.

In the result of deformation, the original grain size was significantly reduced from 7 mm to 4.5 μm. All samples demonstrated the formation of the bimodal structure where the large grains are surrounded by smaller ones. The processes of fragmentation and continuous dynamic recrystallization play the main role in the grain refinement. With the increase of deformation degree, the basis texture (0001) strengthens. The authors did not find any traces of the intense twinning, which is one of the main deformation mechanisms in magnesium. Tensile tests showed the improvement of plastic properties of 120-μm foil compared to a 1-mm plate.

About the authors

Darya Arkadievna Komkova

postgraduate student, leading engineer of Laboratory of strength

Author for correspondence.
Email: komkova_d@imp.uran.ru

M.N. Mikheev Institute of Metal Physics of Ural Branch of the Russian Academy of Sciences, Yekaterinburg

Russian Federation

Aleksey Yurievich Volkov

M.N. Mikheev Institute of Metal Physics of Ural Branch of the Russian Academy of Sciences, Yekaterinburg

Email: volkov@imp.uran.ru

Doctor of Sciences (Engineering), Head of Laboratory of strength

Russian Federation

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