Materials Research and Technology

Shape Memory Alloys & Shape Memory Polymers

Shape Memory Alloys have mostly two phases Austenite and Martensite. Austenite phase is symmetric and Martensite phase is less symmetric. When a SMA is in martensite phase at lower temperatures, the metal can be deformed easily into any shape. When the alloy is warmed, it goes through transformation from martensite to austenite. Shape memory alloys are special and unique class of metal alloys when warmed up above certain temperature can recuperate apparent lasting strains which are resulted in it. They have high strength, good elasticity, fatigue resistance, wear resistance, easy fabrication. SMA’s have the ability to be used successfully in seismic area.

The two most prominent shape-memory alloys are copper-aluminum-nickel and nickel-titanium (NiTi), but SMAs can also be developed by alloying zinc, copper, gold and iron.

Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their permanent shape develop by an external stimulus, such as temperature change. Shape Memory polymers are the compound plastics polymers that have a unique chemical structure. The glass transition temperature (Tg) plays a crucial role in Shape Memory Polymers. Above the Tg these Shape Memory polymers turn into rubber elastic and flexible. These Materials can solve engineering problems with unbelievable efficiency.

Here are the examples of polymers which can exhibit shape memory effect include(meth)acrylates, polyurethanes, and blends of polyurethane and polyvinylechloride.