Thermodynamics of ‘ESR’ slag for producing nickel alloys

Abstract

Ni-base alloys have been used for steam turbine in power plant that operates at temperatures higher than 873 K due to their high strength and superior heat resistance. Commercially, nickel alloys are generally produced by ESR (Electro-Slag Remelting) process with high cleanliness. During the ESR process, however, several alloying elements such as Ti and Al react with molten slag (2Ti+Al2O3=2Al+Ti2O3), resulting in a different composition between electrode and solidified ingot. Therefore, in the present study, we investigated the equilibrium between CaO-Al2O3-CaF2-TiOxtype ESR slag and Ni-Ti-Al(-C) alloys at 1773 K to minimize the change in the alloy composition during ESR process. © 2016 by The Minerals, Metals & Materials Society.