Effects of cooling rate on the solidification and microstructure of nickel-based superalloy GTD222

Abstract

In thiswork, themicrostructure and solidification behavior of nickel-based superalloyGTD222 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.