Effect of heat treatment on tension-compression yield asymmetry of AZ80 magnesium alloy

The tension-compression yield asymmetry of extruded AZ80 alloy under different heat treatments was studied using uniaxial tensile and compressive tests at room temperature. It was found that aging treatment was much more effective in reducing the asymmetry than solution treatment. Finer twins and lower twin volume fraction in aged alloy were observed by optical microscope and X-ray diffraction. In order to understand the tiny effect of solution treatment on the asymmetry, quadrangular prism-shaped atomic group unit model was used to show that alloying elements in solution suppressed the {10-12} twinning. The smaller grain size also inhibited twinning during deformation. On the other hand, the macroscopical interaction between the precipitation and twin was proposed to illustrate the significant impact of aging treatment on the asymmetry. (C) 2011 Elsevier Ltd. All rights reserved.