The High-Temperature Deformation Mechanism in Al-Mg Alloys and the Internal Stress

Average internal stresses measured by the dip test in high-temperature deformation of Al-Mg alloys have been known to be very high compared with those estimated from the assumption of the equi-distant distribution of parallel dislocations.In order to examine the validity of the dip test, stress relaxation and rapid strain rate change tests were performed in Al-5.7 at%Mg, and the high internal stresses were confirmed.The dislocation density and the distribution in the steady-state deformation were estimated theoretically based on the solute atmosphere dragging mechanism, and the average internal stress was calculated from the dislocation distribution. It is concluded that the high internal stress is due to forest dislocations existing in high density.