Regular Article

Non-metallic inclusions in a superalloy during refining through cold crucible levitation melting process

¹ School of Mechanical Engineering, Yanshan University, Qinhuangdao City, Hebei Province 066004, China
² Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
³ School of Mechanical and Materials Engineering, North China University of Technology, Beijing, 100144, China

^* e-mail: zlin@ustb.edu.cn
^** e-mail: zhanglifeng@ncut.edu.cn

Received: 10 August 2021
Accepted: 31 January 2022

Abstract

Oxide and nitride inclusions in a Ni-based superalloy during the cold crucible levitation melting (CCLM) process were investigated towards a better understanding for the removal of inclusions from the metal. The number, morphology, size distribution and spatial distribution of inclusions were characterized using an automated scanning electron microscopy with energy-dispersive X-ray spectroscopy. Inclusions in the alloy were efficiently agglomerated and removed by floating during CCLM process. Inclusion clusters as big as 30-400 ?m were observed. Oxide clusters were efficiently floated during pouring process. The removal ratios of oxides were about 21% without pouring and 62% with pouring, respectively. Additionally, CCLM promotes the separation of oxides from nitrides. The effect of CCLM on the removal of nitride inclusions is not such evident compared with oxides. The mechanism of inclusion removal during CCLM was clarified.