Coarsening Behavior of Al3（Sc, Zr） Precipitates and Its Influence on Recrystallization Temperature of Al-Mg-Sc-Zr Alloy

Effects of intermediate annealing temperature and time after hot working on recrystallization temperature (Tr) of Al-Mg-Sc-Zr alloy subjected to further cold working were investigated. It was found that Tr of cold worked alloy dropped with the rise of intermediate annealing temperature or extension of annealing time, due to coarsening of Al3(Sc, Zr) particles during intermediate annealing. After annealed at 550°C for 1 h or 475°C for 50 h, Tr is nearly same as that in a Sc, Zr free 5A06 alloy. Coarsening mechanism was also discussed. After hot rolling, residual dislocations promoted diffusion of Sc and Zr atoms at the elevated temperature of the intermediate annealing. Easier diffusion sped the growth of the Al3(Sc, Zr) particles, resulting in a coherency loss and quantity reduction of the particles.