The Effect of Small Particles during Recrystallization of Cold Worked AA6061 and AA7032 Aluminium Alloys

摘要

The isothermal annealing behaviour of AA6061 and AA7032 alloys after cold deformation has been investigated for a range of temperatures. Shorter recrystallization times were consistently observed in the AA6061 alloy, although abnormally slow kinetics were encountered during low temperature annealing of AA7032. Furthermore, calculated activation energy values were slightly higher in AA7032. These results have been discussed in terms of the second phase particles present in the microstructure, which were characterised by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The difference between the two alloys was attributed to the distribution of chromium-rich dispersoid particles and their consequent effectiveness in retarding the recovery and recrystallization processes. Recrystallization occurred readily at all temperatures in AA6061 despite Mg_2Si precipitation, whilst a change in mechanism to continuous recrystallization is proposed to explain the low temperature AA7032 behaviour.