Original Article

Synergistic effect of MgO and CeO₂ in the slag on non-metallic inclusions of high Al nickel-based superalloy during electroslag remelting

School of Mechanical Engineering, Yanshan University, Qinhuangdao City, Hebei Province 066004, PR China

^* e-mail: gaoxiaoyong@ysu.edu.cn

Received: 5 April 2025
Accepted: 30 May 2025

Abstract

The effect of MgO and CeO₂ in the slag on the modification and removal of non-metallic inclusions in a high Al nickel-based superalloy during electroslag remelting was investigated. Chemical reactions between MgO and CeO₂ in the slag and dissolved Al in the alloy led to dissolved Ce and Mg. Dissolved Mg changed original polygonal MgO-Al₂O₃ inclusions to spherical MgO-Al₂O₃ with increasing MgO content, while dissolved Ce replaced Mg and Al of the inclusions and changed inclusions to Ce₂O₃-Al₂O₃-MgO. The content of O and the number of inclusions decreased significantly in case of rare earth bearing slag with high CeO₂/Al₂O₃ mass ratio. The whole interfacial reactions were: MgO(slag) + CeO₂(slag) + 2[Al]_Ni(l) = Al₂O₃(slag) + [Mg]_Ni(l) + [Ce]_Ni(l), and Al₂O₃ (inclusion) + [Mg]_Ni(l) + [Ce]_Ni(l) = MgO(inclusion) + CeO₂(inclusion) + [Al]_Ni(l).