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Indexed by:期刊论文

Date of Publication:2019-08-01

Journal:VACUUM

Included Journals:SCIE、EI

Volume:166

Page Number:107-113

ISSN No.:0042-207X

Key Words:Ni-based superalloy; Elements dispersion; The marangoni effect; Diffusion; Electron beam remelting

Abstract:The dispersion of alloying elements in superalloy during Electron Beam Technology (EBT) is an important and unreported issue. In order to investigate this problem, dispersion of alloying elements and the corresponding influence on y phase and hardness are investigated for K417 Ni-based superalloy remelted by EBT in which the vacuum is kept at 2-5 x 10(-2) Pa. Cr, Ti and Mo segregate obvious after remelting. Especially for Cr, its concentration increases to 8.200 wt% in upper layer of melt alloy after melting procedure and ultimately decreases to 6.740 wt%; the concentration in lower part ultimately increases to 8.599 wt%, which is much higher than origin concentration of 7.906 wt%.The increase of Cr in lower part gives rise to strength of gamma phase, therefore increasing micro-hardness. Sharp temperature gradient in the melt and the Marangoni effect dominate the dispersion of alloying elements before the temperature of melt reaching ebullition point. Ebullition of the melt completely counteracts the Marangoni effect and move elements gathered by temperature gradient to the bottom of melt. The results of the investigation will help guide the application of electron beam technology on Cr contained superalloy for the dispersion mechanisms.