Effects of Al-5Ti-1B grain refiner on solidification microstructure of 7A04 aluminum alloy

The effects of different amounts of Al-5Ti-1B grain refiner on microstructure and secondary solidification of 7A04 aluminum alloy semisolid slurry were investigated. The results show that the primary α-Al particles of 7A04 aluminum alloy semisolid slurry become fine and globular by adding 0.1% Al-5Ti-1B grain refiner. The microstructure with average particle diameter 71 μm and shape factor 0.49 of primary α-Al particles at 630 °C could be obtained. When the amount of Al-5Ti-1B grain refiner is higher than 0.1%, the effect of refining is not obvious. As the temperature increases, the microstructure of semisolid slurry of 7A04 aluminum alloy gets fine but the shape factor deteriorates. The microstructure of semisolid solidification with fine and globular α₂ particles could be achieved by addition of Al-5Ti-1B grain refiner, but there is little change for average particle diameter and shape factor of α₃ particles.