Abstract:The microstructure evolution of Al–Sr master alloy during continuous extrusion was investigated using X-ray diffractometer, scanning electron microscope and transmission electron microscope. Results indicate that the continuous extrusion process could change the Al₄Sr particles of the alloy significantly in size and morphology. The as-cast needle-like Al₄Sr particles are broken into small blocks in upsetting zone and crushed heavily in adhesion zone. Plenty of dislocations get tangled up in right-angle bending zone. Al₄Sr particles grow in the extending zone. Finally, Al₄Sr particles in products are approximately 28 μm in length. Al₂Sr particles precipitate during the process. Compared with products by horizontal extrusion, Al₄Sr particles by continuous extrusion are finer and distribute more evenly.

Key words: Al-Sr master alloy; grain refiner; continuous extrusion; microstructure evolution