Electron beam melt superheating treatment (EBMST) is firstly proposed to prepare DZ125 alloy, which opens up a new way to further explore and improve the properties of superalloys. The effects of melt superheating treatment at ultra-high temperature on the composition, microstructure and purity of superalloy were studied. As the melt superheating power increases, the mass loss rate of the alloy increases gradually. A theoretical model for controlling alloy composition was established. The secondary dendrite spacing, the area fraction of the eutectic structure and the size of γ′ phases decrease first and then increase with the increase of the melt superheating power. The sizes of γ′ phases at dendritic core and interdendritic regions have the minimum values of 0.12 μm and 0.16 μm, respectively. As the melt superheating power increases, the segregation coefficients of Co and W increase first and then decrease, while that of Ti and Mo decrease first and then increase. The best purification effect is achieved at 14 kW, where the content of O and N are 1.8 ppmw and 1.2 ppmw, respectively. It means that 78% O and 80% N are removed from the raw materials.
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