Atom probe tomography analysis is available at UIUC with the Cameca LEAP 5000XS instrument. Two focused ion beam instruments, a THERMO SCIOS2 dual-beam SEM/FIB and a FEI Helios 600i dual-beam SEM/FIB, are available for sample preparation.
We have performed APT analysis of 308L weldment groove filler material. This material undergoes recrystallization during the welding process and forms both delta ferrite and gamma austenite. The mixed phase is crucial to preventing cracking during solidification of the weldment. We have discovered that proton irradiation of this material results in the precipitation of the G phase in delta ferrite and Ni-Si clusters in gamma austenite [G phase/clustering in 308L]. Further, slow strain rate immersion testing demonstrates that irradiation-assisted stress corrosion cracking, a critical degradation mechanism for weld repairs in nuclear power plants, occurs by crack nucleation and growth along the delta-gamma phase boundaries. Radiation-induced segregation is associated with these boundaries and likely contributes to the observed IASCC. This is discussed in greater detail in the research highlight related to IASCC.
The first three videos show FIB fabrication of a APT tip. The next three videos are renderings of various elements found in APT analysis.
The project is sponsored by the US DOE NEUP.