Influence of melt superheating treatment temperature on solute distribution behavior ofanew ni-based single crystal superalloys

Solute partition coefficient plays an important role in determining the microstructure and mechanical properties of Ni-based superalloys. Melt superheating treatment can greatly affect the melt structure and redistribution of solute atom in the melt. However, up to date, there are few investigations of the influence of melt superheating treatment on the solute partition coefficient, especially for the new-generation Ni-based single crystal superalloy with additions of Re and Ru. Therefore, in this work, the influence of melt superheating treatment temperature on the solute partition coefficient of a new Ni-based single crystal superalloy with Re and Ru elements under planar solid/liquid (S/L) interface under directional solidification conditions was systematically investigated by using EPMA. It was found that the distribution of solute elements, such as Al, Ta, Ru, Re, W, Co, showed remarkable change in both sides of the S/L interface with increasing melt superheating treatment temperature, but there was little change for the solute elements of Mo and Cr. With increasing the melt superheating treatment temperature, the concentration of solute elements for Al and Ta increased firstly and then decreased, but it showed an opposite trend for Re, W, Ru and Co. Additionally, the change of the solute partition coefficients for Ru, Co, Mo and Cr were small with increasing the melt superheating treatment temperature. The main reasons related to the above changes can be ascribed to that the variation of melt superheating treatment temperature affects the size of the atom clusters in melt, which gives rise to the variation of atomic distribution, and thus leads to the change of solute partition coefficients.