Recrystallisation resistance of extruded and cold rolled aluminium alloys with additions of Hf, Sc and Zr

A high recrystallisation resistance is required in aluminium alloys intended for processing or use at temperatures between 450 degrees C-600 degrees C. Additions of Hf, Sc and Zr significantly improve the resistance to recrystallisation through the formation of Al3X-dispersoids (X=Hf,Sc,Zr), and in this work different concentrations and combinations of these elements were added to five aluminium alloys. The alloys were extruded, subjected to various degrees of cold rolling (0%-80%) and finally annealed at high temperatures in order to study the structural stability. All variants displayed a high resistance towards recrystallisation, but the best results were obtained in the alloy containing only Sc and Zr. In this alloy no signs of recrystallisation were observed even after I hour annealing of extruded and 80% cold rolled profiles at 600 degrees C.