Atom probe analysis of nickel-based superalloy IN-718 with boron and phosphorus additions

The effects of controlled additions of boron and phosphorus to nickel-based superalloy IN-718 have been investigated by atom probe field ion microscopy in specimens subjected to a long term heat treatment (6 months at 704°C). The predominant γ, γ′ and γ′′ phases were found to be depleted in boron and phosphorus, and no segregation was detected at γ–γ′ and γ–γ′′ interfaces. Significant phosphorus enrichments were found in the minor σ and Laves phases.