Study of twin-roll cast Aluminium alloys subjected to severe plastic deformation by equal channel angular pressing
Abstrakt
Aluminium alloys prepared by twin-roll casting method become widely used in industry applications. Their high solid solution supersaturation and finer grains ensure better mechanical properties when compared with the direct-chill cast ones.
One of the possibilities how to enhance their thermal stability is the addition of zirconium. After heat treatment Al3Zr precipitates form and these pin moving grain boundaries when the material is exposed to higher temperatures.
In the present work twin-roll cast aluminium alloys based on AA3003 with and without Zr addition were annealed for 8 hours at 450 degrees C to enable precipitation of Al3Zr phase. Afterwards they were subjected to severe plastic deformation by equal channel angular pressing, which led to the reduction of average grain size under 1 mu m.
During subsequent isochronal annealing recovery and recrystallization took place. These processes were monitored by microhardness measurements, light optical microscopy and in-situ transmission electron microscopy.
The addition of Zr stabilizes the grain size and increases the recrystallization temperature by 100 degrees C.