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

Atom-probe techniques were used to study grain boundary segregation and interphase interfaces (gamma/gamma') in nickel base superalloys. Experiments conducted with a conventional atom-probe reveal a strong enrichment 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 close vicinity of gamma/gamma' interfaces are also reported. The 3D reconstruction of a small volume of superalloy on a near atomic scale illustrates the performance of the Tomographic Atom-Probe recently developed, in atomic imaging of interfaces.