Advanced Shape Memory Alloys Processed by Powder Metallurgy

Abstract

In recent years there has been an increasing attention to the development and research of so-called ªsmart materialsº. These new kind of materials appeared as a result of the synthesis of structural and functional materials combined with the integration of a control mechanism.Some of the most interesting materials in this class are shape memory alloys(SMA). This is due to the unique and special functional properties exhibited by SMA: one-way shape memory effect, twoway shape memory effect, constraint recovery thereby creating a high (recovery) force, pseudoelasticity, and high damping capacity. Several SMA families can be found, such as Ni-Ti, Cu-Zn-Al, Cu-Al-Ni, Fe-Mn-Si,. The properties of these alloys can be changed and controlled by means of the thermomechanical processing of the material, so that they exhibit the desired properties. Nowadays, Ti-Ni and Cu-Zn-Al are the most used families in practical applications. However, they cannot be used for high temperature applications (above 100 ºC).[3] For that reason there has lately been an increasing effort in the development of alloys overcoming these limitations.