Investigation of microstructural changes in INCONEL 706 at high temperatures by in-situ small-angle neutron scattering

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2003-12, Vol.34 (12), p.2781-2792
• Main Authors: MUKHERJI, D, STRUNZ, P, DEL GENOVESE, D, GILLES, R, RÖSLER, J, WIEDENMANN, A
• Format: Article
• Language: English
• Subjects: Alloys; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Heat treating; Materials science; Neutrons; Physics; Plating; Solid solution hardening, precipitation hardening, and dispersion hardening; aging; Solid solution, precipitation, and dispersion hardening; aging; Treatment of materials and its effects on microstructure and properties
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-003-0179-9

The Ni-Fe based superalloy INCONEL 706 (IN706) has a complex microstructure and many A^sub 3^B type phases, e.g., Ni^sub 3^Al [gamma]', Ni^sub 3^Nb [gamma]'', Ni^sub 3^Nb [delta], or Ni^sub 3^Ti [eta] precipitates can form. The various precipitates can also have different morphologies, i.e., plate, needle, cube, or disc shape, and some of them exist as co-precipitates-[gamma]'/[gamma]''. In the present study, in-situ measurements by small-angle neutron scattering (SANS) were performed to monitor the microstructural evolution at elevated temperatures. The SANS measurements were complemented by microstructural observations at room temperature by scanning electron microscopy and transmission electron microscopy (SEM and TEM). It is demonstrated that [eta] plates and [gamma]' needles form directly at high temperatures. Cooling from high temperature produces fine dispersions of [gamma]'/[gamma]'' precipitates, which coarsen on reheating to lower stabilization temperatures (893 and 993 K). The final morphology of the [gamma]'/[gamma]'' co-precipitates, i.e., compact/noncompact type very much depends on the stabilization temperature and the cooling rates from prior higher-temperature stabilization steps. [PUBLICATION ABSTRACT]