Microstructure Evolution and Phase Identification in Ni-Based Superalloy Bonded by Transient Liquid Phase Bonding

Mariana Poliserpi*, Ricardo Buzolin, Roberto Boeri, Cecilia Poletti, Silvana Sommadossi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This study investigates the development of the microstructure in the interconnection zone of an IN718/Al/IN718 couple obtained by the Transient Liquid Phase Bonding (TLPB) process at 1000 °C. The crystal structure, composition and orientation of the phases formed during joining were examined by SEM-EDS EBSD. The results showed that the interconnection zone is a multilayered region, constituted mainly by sigma (σ), Laves and α-Cr phases and the AlNi intermetallic. The evolution of the microstructure over time shows that the topologically close-packed (TCP) phases grow as columnar grains, while the AlNi phase forms exiaquied grains. The AlNi phase is split into two layers, Al-rich and Ni-rich, both having the same crystal structure but different chemical composition. EBSD mapping revealed that there is no grain boundary along the split line, suggesting that splitting results from a solid-state transformation requiring no nucleation. At longer bonding time, the AlNi phase is enriched in Ni and presents nanoprecipitates homogeneosly dispersed. These results provide experimental data that contribute to the understanding of TLPB of superalloys.

Original languageEnglish
Pages (from-to)1695-1707
Number of pages13
JournalMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
Issue number3
Publication statusPublished - Jun 2021

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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