Creep behavior of AJ62 Magnesium–Aluminum–Strontium alloy

Abstract

Creep tests were conducted in uniaxial compression to evaluate the creep behavior of magnesium–aluminum–strontium alloy at temperatures from 373 to 673 K. Stress dependencies of the creep rate over the whole interval of temperatures and stresses can be well described phenomenologically by the Garofalo sine hyperbolic equation modified by the inclusion of a threshold stress. The threshold stress increases with decreasing temperature. Creep data normalized by a diffusion coefficient and shear modulus clearly reveal the existence of two different regions. Possible mechanisms by which plastic deformation takes place have been identified in both regions. The critical stress at which dislocations break away from the cloud of foreign atoms agrees well with the value determined by data normalization. At low stresses, a value of the stress exponent of n≅3 is consistent with the model of deformation that takes place through dislocation glide controlled by dragging of solute atoms. At high stresses, the multiple regression yields the activation energy which agrees with that for prismatic glide.

Keywords

• Dislocations
• Diffusion
• Mechanical properties
• Creep