Formation mechanism of film-like spinel inclusions in Ni-based superalloys from MgO crucible reactionOA
Film-like MgAl_(2)O_(4) spinel inclusions are among the most harmful oxide defects in Ni-based superalloys because their high aspect ratio exacerbates local stress concentration.In this work,K492M Ni-based superalloy was remelted and cast in a MgO-containing crucible using a vacuum induction furnace to clarify the origin and formation pathway of Mg-,Al-,and O-bearing inclusions.Scanning electron microscopy,transmission electron microscopy,energy-dispersive spectroscopy,and selected-area electron diffraction were used to characterize the morphology,composition,and crystal structure of the inclusions.The results show that the inclusions consist mainly of particulate MgO cores directly coated by MgAl_(2)O_(4) shells,together with flocculent film-like MgAl_(2)O_(4)products extending outward from the cores.Only local residualα-Al_(2)O_(3) is detected,indicating that Al_(2)O_(3) is a transient intermediate rather than a stable final product.Based on these observations,a three-stage mechanism is proposed:mechanical spallation of MgO particles from the crucible wall,rapid interfacial reduction coupled with solid-state transformation to form MgAl_(2)O_(4),and stress-induced rupture and exfoliation of the spinel shell into thin films.This mechanism explains the coexistence of MgO-MgAl_(2)O_(4) core-shell particles and film-like spinel inclusions,and provides guidance for controlling crucible-derived oxide contamination in Ni-based superalloy castings.
Wen-jin Wu;Feng-wei Guo;Wei-jie Xing;Li-hui Zhang;Min Xia;Xiao-dong Ren;Lei Qian
Science and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,ChinaScience and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,ChinaScience and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,ChinaScience and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,ChinaInstitute of Powder Metallurgy and Advanced Ceramics,University of Science and Technology Beijing,Beijing 100083,ChinaScience and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,ChinaScience and Technology on Advanced High Temperature Structural Materials Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,China
矿业与冶金
K492M alloyNi-based superalloyvacuum induction remeltingMgO crucibleMgAl_(2)O_(4)spinelfilm-like inclusioninterfacial reaction
《China Foundry》 2026 (4)
P.591-598,8
financially supported by the National Key Research and Development Program of China(Grant No.2022YFB3708100)the WDZC program of BIAM(Grant No.2019-363)the National Natural Science Foundation of China(Grant No.52374360)。
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