Thermal stability of Al3(Scx,Zr1−x)-dispersoids in extruded aluminium alloys

✍ Scribed by B. Forbord; H. Hallem; J. Røyset; K. Marthinsen

• Book ID: 103842647
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 762 KB
• Volume: 475
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2007.04.054

✦ Synopsis

In aluminium alloys the highest resistance against recrystallisation is obtained through combined additions of Sc and Zr. Upon annealing these elements form a high number density of homogeneously distributed and coherent Al 3 (Sc x Zr 1-x )-L1 2 -dispersoids, and the coarsening of these phases subsequently control the softening processes of recovery and recrystallisation. In this work the kinetics of Al 3 (Sc x Zr 1-x )-coarsening has been investigated during annealing of two precipitation annealed and extruded Al-(Mn)-Fe-Si-Sc-Zr-alloys at temperatures between 500 • C and 600 • C. A simple analysis based on widely used theories for volume diffusion controlled dispersoid coarsening (R 3 (t) -R 0 3 ∝ t) was used to identify the dominant mechanisms. It was found that coarsening in both alloys is controlled by volume diffusion of Zr, as activation energies, Q, of 285 ± 31 kJ/mol and 250 ± 43 kJ/mol were obtained, respectively.