Effect of cooling rate on morphology and type of vanadium-containing phases in Al-10V master alloy.

Effects of cooling rates on the morphology, sizes and species of primary vanadium-containing phases in Al-10V master alloys were investigated. The results show that the primary vanadium-containing phases with different morphologies and compositions present in Al-10V master alloys at different cooling rates with the pouring temperature of 1,170 °C. When the Al-10V master alloy is solidified in the refractory mold at a cooling rate of 2 °C·s^-1, the vanadium-containing phases are mainly plate-like Al10V phases, with the average size of 100.0 µm in the center and 93.2 µm at the edge of the ingot. When the master alloy is solidified in the graphite mold at a cooling rate of 24.3 °C·s^-1, the primary vanadium-containing phases are dendritic Al3V phases, with the average length of 297.0 µm for the first dendrite in the center and 275.0 µm at the edge of the ingot. The secondary dendrite arm spacing (SDAS) is 9.5 µm in the center and 9.3 µm at the edge of the ingot, respectively. When the solidification is carried out in the copper mould at a cooling rate of 45.7 °C·s^-1, the primary vanadium-containing phases are also Al3V phases but with smaller size, compared with that prepared at the cooling rate of 24.3 °C·s^-1. As a result, the average length is 190.0 µm for the first dendrite in the center and 150.0 µm at the edge of the ingot. The SDAS is 9.8 µm in the center and 4.4 µm at the edge of the ingot, respectively. [ABSTRACT FROM AUTHOR]