The crystallography of α-iron deposited onto the (112) plane of a Cu-Ni alloy

A thin α-iron film was vacuum deposited onto the (112) plane of a Cu-47 at.% Ni alloy substrate. Transmission electron microscopy revealed that the α-iron existed in two twin-related variants having the Kurdjumov-Sachs orientation relationship with the f.c.c. substrate. The boundaries between the two variants appeared parallel to the [110] direction on the (112) plane. The crystallography and morphology of the α-iron thin film can be excellently explained through a simple geometrical consideration of an optimum matching between the two crystals at the interface.