1 Microstructure , texture and tensile properties of ultrafine / nano grained 1 magnesium alloy processed by accumulative back extrusion

Microstructure, texture and tensile properties of ultrafine/nano grained 1 magnesium alloy processed by accumulative back extrusion 2 3 S.M. Fatemi, A. Zarei-Hanzaki, J.M. Cabrera 4 5 a School of Mechanical Engineering, Shahid Rajaee Teacher Training University, 136-16785, Tehran, Iran 6 b Department of Metallurgical & Materials Engineering, University of Tehran, 515-14395, Tehran, Iran 7 c Departamento de Ciencia de Materiales e Ingeniería Metalúrgica, ETSEIB, Polytecnic University of Catalonia, Av. Diagonal, 64708028, Barcelona, Spain 8 Abstract 9 An AZ31 wrought magnesium alloy was processed by employing multipass accumulative 10 back extrusion process. The obtained microstructure, texture and room temperature tensile 11 properties were characterized and discussed. Ultrafine grained microstructure including nano 12 grains were developed, where the obtained mean grain size was decreased from 8 to 0.5 μm by 13 applying consecutive passes. The frequency of both low angle and high angle boundaries 14 increased after processing. Strength of the experimental alloy was decreased after processing, 15 which was attributed to the obtained texture involving the major component lying inclined to the 16 deformation axis. Both the uniform and post uniform elongations of the processed materials were 17 increased after processing, where a total elongation of 68 pct was obtained after six-pass 18 deformation. The contribution of different twinning and slip mechanism was described by 19 calculating corresponding Schmid factors. The operation of prismatic slip was considered as the 20 major deformation contributor. The significant increase in post uniform deformation of the 21 processed material was discussed relying on the occurrence of grain boundary sliding associated 22 with the operation of prismatic slip. 23