Observation of the shape memory effect and thermoelastic martensitic transition in the nano-scale at Ti$_2$NiCu alloy in a transmission electron microscope

For the first time in a transmission electron microscope during heating and cooling, the reversible shape memory effect in composite amorphous-crystalline Ti$_2$NiCu samples was demonstrated while observing the evolution of the structure of martensitic twins and changes in shape. The studies were carried out on very thin wedge-shaped specimens with varying thickness from $200$ to $20$ nm, made in the form of a composite bimetallic nano-actuator using an original technique of local etching and polishing with a focused ion beam.