Study of precipitated phases in a Fe-Ni-Co base superalloy Conference Paper uri icon

abstract

  • It is continuously sought in superalloys to increase the mechanical strength at high working temperatures for longer time periods. Superalloys get their mechanical properties mainly with a suitable controlled thermomechanical process, heat treatment, precipitation mechanism and chemical composition. The precipitation mechanism in an Incoloy 909 superalloy includes the formation of phases like γ, γ′, η, Laves and carbides and in some cases the precipitation of the ε phase. The presence of ε phase strongly depends on the thermomechanical processing route of the alloy. These phases greatly influence the final mechanical performance of the material. The main objective of this work is to determinate the presence of the ε phase in an Incoloy 909 alloy which was forged under different thermomechanical parameters. The material was forged either at 900 or 1060°C Subsequently the alloy was solubilized and age heat treated; mechanical compression testing was carried out to promote precipitation of secondary phases. These phases were qualitatively evaluated using optical microscopy (OM), scanning and transmission electron microscopy (SEM and TEM) and chemical composition maps using energy dispersive spectroscopy (EDS). It was observed that the Nb and Si elements segregate particularly on the precipitates even after heat treatments and compression testing. The electron diffraction patterns were indexed and the crystallographic information obtained was related to the presence of ε, γ′ and γ matrix. Copyright © 2011 MS%26T'11®.
  • It is continuously sought in superalloys to increase the mechanical strength at high working temperatures for longer time periods. Superalloys get their mechanical properties mainly with a suitable controlled thermomechanical process, heat treatment, precipitation mechanism and chemical composition. The precipitation mechanism in an Incoloy 909 superalloy includes the formation of phases like γ, γ′, η, Laves and carbides and in some cases the precipitation of the ε phase. The presence of ε phase strongly depends on the thermomechanical processing route of the alloy. These phases greatly influence the final mechanical performance of the material. The main objective of this work is to determinate the presence of the ε phase in an Incoloy 909 alloy which was forged under different thermomechanical parameters. The material was forged either at 900 or 1060°C Subsequently the alloy was solubilized and age heat treated; mechanical compression testing was carried out to promote precipitation of secondary phases. These phases were qualitatively evaluated using optical microscopy (OM), scanning and transmission electron microscopy (SEM and TEM) and chemical composition maps using energy dispersive spectroscopy (EDS). It was observed that the Nb and Si elements segregate particularly on the precipitates even after heat treatments and compression testing. The electron diffraction patterns were indexed and the crystallographic information obtained was related to the presence of ε, γ′ and γ matrix. Copyright © 2011 MS&T%2711®.

publication date

  • 2011-01-01