MICROSCOPY AND MICROANALYSIS OF INTERFACES ON A SUBNANOMETRIC SCALE WITH THE ATOM-PROBE

Atom-probe techniques were used to study grain boundary segregation an d interphase interfaces (gamma/gamma') in nickel base superalloys. Exp eriments conducted with a conventional atom-probe reveal a strong enri chment of boron and molybdenum in Astroloy superalloys. The influence of heat treatment on the geometry and local chemistry of boundaries is discussed. Non-equilibrium concentration gradients observed in the cl ose vicinity of gamma/gamma' interfaces are also reported. The 3D reco nstruction of a small volume of superalloy on a near atomic scale illu strates the performance of the Tomographic Atom-Probe recently develop ed, in atomic imaging of interfaces.