Precursor state in a Ti₅₀Pd₃₄Fe₁₆ alloy studied by advanced transmission electron microscopy

Peculiar diffuse scattering and microstructures, which occur prior to the onset of a B2 → 4H transformation in a Ti₅₀Pd₃₄Fe₁₆ alloy, have been intensively studied by energy-filtered electron microscopy and high-resolution electron microscopy. Two types of diffuse scattering, i.e., rod-like diffuse scattering emanating from the fundamental reflection and a satellite at the tip of the rod, were observed. The rod-like diffuse scattering appeared to be due to well-known tweed microstructures, while the satellite to characteristic microdomains as discovered in a Ti₅₀Ni₄₈Fe₂ alloy. A dark-field image showed a trend of regular array of the microdomains along <110> directions. This array is likely to correspond to striations observed in the tweed microstructures.