After mechanical deformation the alloy is able to recover its original shape through thermal evolution.
We observe this effect (fig.1) when the alloy is subjected to thermo mechanical load corresponding to sequences (a)+(b)+(c) (fig.2).
The principle of memory effect -one way is as follow:
- Sequence (a) : Cooling without constraint starting from a temperature Ti higher than Ms up to final temperature Tf below Mf. During this sequence martensite is created but transformation deformation is null.
- Sequence (b) : Constraint (charge and discharge) at constant temperature. There is no phase transformation but reorientation of martensite variant created during cooling.
- Sequence (c) : Heating until temperature Ti without constraint. The alloy recovers its original shape.