In-situ transmission electron microscopy determination of solid-state diffusion in the aluminum-nickel system

Using in-situ techniques, which couple energy dispersive spectroscopy mapping with a heated transmission electron microscope stage, solid-state diffusion of Ni-Al is studied in the temperature range 623–723 K with characteristic diffusion lengths of 1–100 nm. When the concentration profiles are analyzed using the Sauer-Freise method, and evaluated for 50 atomic percent Ni, the diffusion coefficients follow an Arrhenius temperature dependence: $D_{Ni\to Al}=8.2\text{x}{10}^{-9}\exp \left(-111kJ/RT\right){\text{m}}^2/\text{s}$. Additionally, the formation of Al-rich intermetallic phases (Al₃Ni & Al₃Ni₂) is shown to occur within heating durations of a second at the studied temperatures.