Effect of melt temperature on the quasi-equilibrium solidification of K465 Ni-based superalloy

The solidification process of Ni-based superalloy K465 was examined using DTA and X-ray diffraction. The impact of melt structure on solidification process and the morphology of MC carbide and gamma ' -phase was analyzed. It was observed that an increase in melt peak temperature led to a significant decrease in precipitation temperature for carbides, but only a slight increase in the formation temperature of matrix and eutectic microstructure. The X-ray diffraction results showed that some ordered structures were detected in the sample with melt peak temperature of 1450 degrees C and 1500 degrees C, but not in the sample with melt peak temperature of 1360 degrees C. Furthermore, the ordered structure displayed similar crystalline features with M 6 C carbide. As the melt peak temperature increased, the carbides changed from block type to script type morphology. This phenomenon was likely caused by the formation of ordered structures at high temperatures. However, the microstructure of gamma matrix and gamma ' precipitates remained unaffected by the melt peak temperature.