After “education” the alloy is able to have two stable positions, one above the critical temperature and another one below this temperature.
The recovery of shape is done in both way.
The two stable shapes are :
- at high temperature (austenite)
- at low temperature (martensite)
The principle of shape memory alloy two ways is :
Following a number of cycles called “education” (fig.1) the alloy obtained has two stable shapes (fig.2).