Investigation on the impression creep properties of a cast Mg-6Al-1Zn magnesium alloy

In the present study, the creep behavior of a cast Mg-6Al-1Zn (AZ61) magnesium alloy was investigated using impression creep technique at the temperature range of 423-495 K under shear modulus normalized stress (sigma(imp)/G) between 0.02 and 0.0425. Based on the obtained results in the applied stress range, the creep behavior of the alloy was divided into two low and high stress regimes. Stress exponent varied in the range of 4-6 and 11-12 at the low and high stress regimes, respectively. Also, creep activation energy (Q) varied in the range of 113-199 kJ/mol and 170-188 kJ/mol at the low and high stress regimes, respectively. The activation energy values obtained at the low stress regime were between activation energy for magnesium lattice self diffusion (135 kJ/mol) and dislocation pipe diffusion (92 kJ/mol). Considering the obtained stress exponents and creep activation energies, it can be stated that the climb controlled dislocation creep and power law breakdown are the dominant creep mechanisms at the low and high stress regimes, respectively. (c) 2013 Elsevier Ltd. All rights reserved.