Effects of Cooling Rate on the Solidification and Microstructure of Nickel-Based Superalloy GTD222

摘要

In this work, the microstructure and solidification behavior of nickel-based superalloy GTD222 at different cooling rates are studied. The solidification of the superalloy GTD222 proceeds as follows: L → L + γ, L → L + γ + MC, L → L + (γ/γ′)-Eutectic and L → η phase. Due to alloying element redistribution, the temperature of the solidus GTD222 superalloy, 1310 °C, is slightly lower than the temperature of the liquidus, which is 1360 °C. It was found that the dendrite arm spacing of the alloy decreased with the increase of the cooling rate from 200 μm at 2.5 K/min to 100 μm at 20 K/min.