Description
Iron-based shape memory alloys such as Fe Ni Co Al X (Ti, Ta, Nb) and Fe Mn Al Ni-X (Ti, Cr), attracted considerable attention due to their unique material properties. Low costs for alloying elements and high reversible transformation strains qualify them for industrial mass applications. Both alloy systems feature unique functional material characteristics. One of the key features of the Fe-Mn-Al-Ni shape memory alloy system is the low temperature dependency of the critical stress for martensitic transformation over a wide temperature range, which is due to its low Clausius Clapeyron slope. The proposed application temperature range of the alloy is between -196°C and about 150°C. Fe-Ni-Co-Al-X (X=Ta,Ti,Nb) shows high reversible strains under a high superimposed stress up to 900 MPa. In both systems, polycrystalline material conditions can be seen as the main drawback in terms of structural stability. Furthermore, data on the thermomechanical pseudoelastic and actuation response are rare in open literature. Thus, thermal and thermomechanical processes need to be qualified in order to guarantee structural stability. The current study focuses on different material conditions following thermal and thermomechanical processing to improve the performance of these alloys for application, also in the polycrystalline state.
