Dynamic Deformation Behaviour and Dislocation Substructure of AZ80 Magnesium Alloy over a Wide Range of Temperatures

Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan

^* Corresponding author: wslee@mail.ncku.edu.tw

Published online: 7 September 2018

Abstract

The high strain rate deformation behaviour and dislocation substructure of AZ80 magnesium alloy are investigated at strain rates of 8x102 s-1, 1.5x103 s-1 and 2.2x103 s-1 and temperatures of-100 ºC, 25 ºC and 300 ºC using a compressive split-Hopkinson pressure bar system. The flow stress, work hardening coefficient, strain rate sensitivity and temperature sensitivity all increase with increasing strain rate or decreasing temperature. Moreover, the dynamic deformation behaviour is well described by the Zerilli-Armstrong hcp constitutive equation. Transmission electron microscopy observations show that the dislocation density increases with a higher strain rate or a lower temperature. Finally, the flow stress varies linearly with the square root of the dislocation density in accordance with the Bailey-Hirsch model.