Transmission Electron Microscopy of Substructures Formed During High-Temperature Creep in Al-Mg Alloys

Microscopy of Substructures Formed Du血g High-Temperature Creep in A1-Mg Alloys．Substructures developed during steady-state creep in polycrystalline A1-Mg alloys cont段ining O．52 to 5．54 atタ6皿agnesiu皿were observed in the temperature range 573 to 673 K． and the stress range 14．7to 68．6 MPa． Under the condition where箆望3(π：the applied-stress exponent of steady-state creep rates)Iong， curved dislocations were distributed homogeneously in the greater part of the grain interior． Subboundaries were observed only in the vicinity of grain boundaries． This region became wider as the concentration of magnesium decreased． In alloys of high concentration of magnesium general feature of dislocation distribution was independent of the applied stress，σc， though the dislocation density，ρ(m『2)，depended greatly onσ。(MPa)；for example，ρ＝1．45×1010σ1 62 in A1-5．54 at％Mg alloy at 573 K：．