Kumar, Manoj and Das, Mitun and Majumdar, Jyotsna Dutta and Manna, Indranil (2020) Development of graded composition and microstructure on Inconel 718 by laser surface alloying with Si, Al and ZrB2 for improvement in high temperature oxidation resistance. Surface & Coatings Technology , 402. Art No-126345. ISSN 0257-8972

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Abstract

The present study evaluates the scope of improvement of oxidation resistance of Inconel 718 (IN718) by laser surface alloying (LSA) with Si, Al and ZrB2 using a 0.5 kW continuous wave Nd-YAG laser. The alloyed zone (AZ) is free of macro-defects (porosity, crack, etc.) and contains microstructural and compositional gradation along vertical depth from the top surface until the AZ-substrate interface. Detailed microstructural and phase evolution studies indicate that the AZ consists of multiple intermetallic phases/compounds of Si, Al or Zr with multi-phase eutectic aggregate including Ni-rich matrix phase. The identity, size, morphology and relative amount of these phases vary with LSA parameters and vertical depth within the AZ. Accordingly, the microhardness profile along depth corroborates such graded microstructure and phase aggregate confined to the AZ. Isothermal oxidation studies at 900 degrees C show significant improvement in oxidation resistance due to LSA in comparison to that of as-received IN718, particularly in case of LSA with Si. Post oxidation studies reveal that the oxide scale consists of adherent oxides like SiO2, Al2O3 or ZrO2, in addition to several intermetallic phases pre-existing in the AZ prior to oxidation. Thus, it follows that the intermetallic phase rich AZ developed by LSA is adherent, defect-free, strong and offers very high resistance to oxidation in IN718 at elevated temperature.

Item Type:	Article
Subjects:	Engineering Materials
Divisions:	Bioceramics & Coating
Depositing User:	Bidhan Chaudhuri
Date Deposited:	25 Jan 2021 07:34
Last Modified:	25 Jan 2021 07:34
URI:	http://cgcri.csircentral.net/id/eprint/4846

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