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Microstructural evolution mechanism during brazing of Hastelloy X superalloy using Ni–Si–B filler metal

Ghasemi, A ; Sharif University of Technology | 2018

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  1. Type of Document: Article
  2. DOI: 10.1080/13621718.2017.1410341
  3. Publisher: Taylor and Francis Ltd , 2018
  4. Abstract:
  5. The paper aims at understanding solidification phenomena and solid state precipitations during diffusion brazing of Hastelloy X nickel base superalloy using a ternary Ni–4.5Si–3.2 B (in wt-%) filler metal. The joint is featured by the formation of Ni-rich solid solution in an isothermal solidification zone, borides/silicide formation during eutectic-type solidification in an athermal solidification zone, on-cooling precipitation of fine nickel silicides in the joint centerline, in situ precipitation of Mo–Cr-rich borides in the diffusion affected zone and grain growth in the heat affected zone. The implication of the phase transformations on the joint properties is discussed. It is shown that Hastelloy X exhibited very fast isothermal solidification which can be attributed to its high Mo and Cr content that promotes in situ boride precipitation during brazing. © 2017 Institute of Materials, Minerals and Mining. Published by Taylor & Francis on behalf of the Institute
  6. Keywords:
  7. Boride ; Brazing ; Nickel base superalloy ; Borides ; Filler metals ; Fillers ; Grain growth ; Heat affected zone ; Isotherms ; Nickel ; Nickel compounds ; Precipitation (chemical) ; Silicides ; Superalloys ; Diffusion brazing ; Diffusion-affected zone ; Hastelloy X ; In-situ precipitation ; Isothermal solidification ; Nickel base superalloy ; Nickel silicide ; Solid state precipitation ; Solidification
  8. Source: Science and Technology of Welding and Joining ; Volume 23, Issue 5 , 2018 , Pages 441-448 ; 13621718 (ISSN)
  9. URL: https://www.tandfonline.com/doi/full/10.1080/13621718.2017.1410341