Creep and stress relaxation of commercial cast magnesium-aluminium-base alloys

The plastic deformation of die cast Mg-Al-based alloys during creep and stress relaxation is of considerable interest with regard to their application in vehicles at temperatures T below 150 C. Due to the limited ductility of these alloys it is necessary to separate the effects of plastic deformation and of fracture. This has been done in the present work by combining tension and compression tests. The results obtained in the creep mode of testing are compared to those obtained in stress relaxation. It will be shown that some basic features of deformation in creep and stress relaxation can be simulated with a simple effective stress model of deformation by dislocation motion. (orig.)