Abstract
Shape memory alloys (SMA in short) exhibit a series of properties which are very different compared to regular metallic materials. One of their main characteristic is the ability to change their geometric shape when subjected to an increase from a low to a high temperature. In certain conditions, this shape change can be reversible, such that the material can “memorize” two geometric shapes: the high temperature shape (the “warm” shape) and the low temperature shape (the “cold” shape). These transformations occur due to an effect known as shape memory effect (SME in short). Moreover, through SME, the material is able to produce mechanical work when shifting from the “cold” shape to the “warm” one [1].
The discovery of these alloys is linked to the highlighting of a specific property which actually pertains to only several of said alloys (being uncommon for a metallic material) and which is known as “rubber-type behavior”.
Many types of SMAs are very expensive, due to their composition (which includes noble metals) and their complex manufacturing technologies.. The most commonly encountered alloys nowadays are Ni-Ti, Cu-Al-Zn and Cu-Al-Ni which are employed in a plethora of practical applications.