Phase composition and grain-boundary segregation in a nickel base superalloy: a preliminary TEM-APFIM investigation

International audienceThe role played by minor elements such as boron or zirconium in the improvement of ductility of a two-phase γ/γ′ nickel base superalloy (NA4) is investigated. TEM, FIM and atom-probe techniques are used in a combined way for the study of grain boundaries and γ/γ′ interfaces. Investigations demonstrate that boron as well as zirconium are preferentially located in the γ solid solution. Microanalyses show that boron segregates at grain boundaries but not zirconium. Local composition gradients for aluminium or nickel are also found in the close vicinity of boundaries. \textcopyright 1991