Charakterizace nanostruktury superslitiny IN738LC po únavě za vysoké teploty

Nanostructure Characterization of IN738LC Superalloy Fatigued at High Temperature

conference paper

en

The nanostructure of Inconel 738LC Ni-superalloy strengthened by trimodal gamma precipitates distribution was investigated after Low Cycle Fatigue (LCF) loading at temperature 700C. Different microscopic techniques as Scanning Electron Microscope (SEM) equipped with STEM detector, transmission Kikuchi diffraction in the SEM, transmission electron microscope (TEM) in the bright field mode and high resolution transmission electron microscopes (HRTEM) in STEM mode were used for the characterization and quantification of superalloy nanostructure. The characteristic morphology of gamma precipitates was examined by ex-situ and in-situ Small Angle Neutron Scattering (SANS) at high temperatures. All adopted microscopic techniques indicate that the morphology of gamma precipitates distributed in the gamma matrix as received state corresponds to two types, i.e. large cuboid-like precipitates with the size around 670 nm, and the spherical precipitates with the diameter 52 nm. After the LCF tests at temperature 700C, the ex-situ SANS measurement yielded additional scattering intensities coming from another small gamma precipitates with estimated size up to 10 nm. Thin foils were observed in SEM equipped with STEM detector, in TEM and HRTEM. These observations documented the size 7 nm and evolution of distribution of these precipitates. It was concluded from in-situ SANS experiments that the smallest gamma precipitates arise regardless the application of the mechanical load. These very small precipitates have profound effect on the LCF resistance of the alloy at 700C since dislocations are effectively pinned by these small gamma precipitates as was directly observed by STEM detector in SEM and using TEM in STEM mode.

Nanostruktura Inconelu 738LC Ni-superslitiny zpevněné distribucí trimodálních gamma s čarou precipitátů byla zkoumána po vysokoteplotním (700C) nízkocyklovém namáhání. Pro charakterizaci a vyhodnocení nanostruktury superslitiny byly použity různé mikroskopické techniky – rastrovací elektronová mikroskopie (SEM) se STEM detektorem, transmisní Kikuchiho diffrakce v SEM módu, transmisní elektronová mikroskopie ve světlém poli a také transmisní elektronová mikroskopie v módu vysokého rozlišení (HRTEM). Charakteristická morfologie precipitátů gamma s čarou byla vyšetřována ex-situ a in-situ maloúhlovým neutronovým rozptylem (SANS) za vysokých teplot.

The nanostructure of Inconel 738LC Ni-superalloy strengthened by trimodal gamma precipitates distribution was investigated after Low Cycle Fatigue (LCF) loading at temperature 700C. Different microscopic techniques as Scanning Electron Microscope (SEM) equipped with STEM detector, transmission Kikuchi diffraction in the SEM, transmission electron microscope (TEM) in the bright field mode and high resolution transmission electron microscopes (HRTEM) in STEM mode were used for the characterization and quantification of superalloy nanostructure. The characteristic morphology of gamma precipitates was examined by ex-situ and in-situ Small Angle Neutron Scattering (SANS) at high temperatures. All adopted microscopic techniques indicate that the morphology of gamma precipitates distributed in the gamma matrix as received state corresponds to two types, i.e. large cuboid-like precipitates with the size around 670 nm, and the spherical precipitates with the diameter 52 nm. After the LCF tests at temperature 700C, the ex-situ SANS measurement yielded additional scattering intensities coming from another small gamma precipitates with estimated size up to 10 nm. Thin foils were observed in SEM equipped with STEM detector, in TEM and HRTEM. These observations documented the size 7 nm and evolution of distribution of these precipitates. It was concluded from in-situ SANS experiments that the smallest gamma precipitates arise regardless the application of the mechanical load. These very small precipitates have profound effect on the LCF resistance of the alloy at 700C since dislocations are effectively pinned by these small gamma precipitates as was directly observed by STEM detector in SEM and using TEM in STEM mode.

superslitiny, nano-precipitace, neutronový rozptyl, STEM detektor, TEM

superalloys, nano-precipitation, neutron scattering, STEM detector, TEM

2013

16.10.2013

Tanger, Ltd.

Czech Republic

978-80-87294-44-4

NEUVEDENO

NANOCON 2013 Conference Proceedings

1

712–717

7