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Thermal processing strategies enabling boride dissolution and gamma prime precipitation in dissimilar nickel-based superalloys transient liquid phase bond

Ghasemi, A ; Sharif University of Technology | 2019

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  1. Type of Document: Article
  2. DOI: 10.1016/j.matdes.2019.108008
  3. Publisher: Elsevier Ltd , 2019
  4. Abstract:
  5. The microstructure of dissimilar transient liquid phase bond between Hastelloy X and IN792 nickel-based superalloys is featured by lack of sufficient formation of γ′ precipitates in the bond-centerline and extensive in-situ precipitation of boride second phases in the diffusion affected zones (DAZ). This paper investigates the impact of two thermal processing strategies, using standard solution treatment and aging of IN792 (STA strategy) and using solution treatment of IN792 followed by a post-bond heat treatment utilizing solution treatment of Hastelloy X and aging treatment of IN792 (SPTA strategy) on the joint microstructure and mechanical properties. The boride precipitates in the DAZ of Hastelloy X showed higher resistance to dissolution rather than those in IN792 which can be attributed to the higher content of the boride former elements in Hastelloy X. Both thermal processing routs resulted in the formation of γ′ strengthened bonds with overmatched hardness compared to the Hastelloy X. However, STPA strategy enabled complete dissolution of borides in DAZ of IN792, significant dissolution of borides in DAZ of Hastelloy X, and development of bimodal γ′ distribution in the IN792 base material. Nevertheless, the grain growth in the Hastelloy X after STPA strategy limits the achievable joint shear strength. © 2019
  6. Keywords:
  7. Boride ; Gamma prime precipitation ; Nickel-based superalloy ; Bonding ; Dissolution ; Grain growth ; Heat treatment ; Liquids ; Mechanical properties ; Microstructure ; Nickel ; Nickel alloys ; Precipitation (chemical) ; Superalloys ; Thermal processing (foods) ; Diffusion-affected zone ; Gamma prime ; In-situ precipitation ; Joint shear strengths ; Nickel- based superalloys ; Processing strategies ; Transient liquid phase ; Transient liquid phase bonding ; Borides
  8. Source: Materials and Design ; Volume 182 , 2019 ; 02641275 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S0264127519304460