Microtension behaviour of lenticular martensite structure of Fe–30 mass% Ni alloy

Microtension testing of an Fe–30Ni alloy revealed that yielding in the lenticular martensite plates is not necessarily caused by the slip system with the highest Schmid factor. Dislocation gliding likely occurred on the slip system parallel to the plane of nanotwins in the lenticular martensite plate. The martensite plate exhibited a critical resolved shear stress of ~190 MPa. Strain accumulation at the variant interfaces between the primary plate and the aggregated fragments led to a unique faceted fracture. This is attributed to anisotropic plasticity in the lenticular martensite plates owing to the interaction of the mobile dislocations with the nanotwins.