The martensite transformation in thin foils of iron-nitrogen alloys

The martensite transformation in thin foils of an iron-nitrogen alloy has been investigated. Under these particular experimental conditions the martensite consists of very thin fibre crystals which me twin orientated. The orientation relationship is [1 10]γ ∥ [1 1 1]α ′ and [001]γ ∥ [1 10]α ′. This is different from all orientation relationships found in bulk materials. The difference is explained by the fact that in thin foils the transformation mechanism is leas hampered by the surrounding parent lattice than in bulk materials. A simple transformation mechanism is deduced consisting of a pure distortion and a half twin shear.