Page 248 - Mechanics of Microelectromechanical Systems

4. Microtransduction: actuation and sensing 235
difference in slope between the two phases over the first deformation stage is
the result of the fact that the austenite is stiffer than the martensite, due to its
higher cubic symmetry, and this is the core feature enabling the utilization of
SMAs as actuators/sensors in macro/micro applications. The martensite
characteristic displays a quasi-horizontal portion (called the
plateau region) where a component in this state can be deformed with
virtually no increase in the external load.

Figure 4.47 Load-deformation characteristics of the martensite and austenite phases of a
typical SMA

Figure 4.48 Superelastic (SE) effect in a shape memory alloy