Revisiting Cu-based shape memory alloys: Recent developments and new perspectives

Abstract

Cu-based shape memory alloys belong to one important class of functional alloys, presenting shape memory effect and superelasticity due to their reversible martensitic transformation. Although they have been extensively studied since the middle of the last century, there are still many challenges to be solved. In the last decades, these alloys were extensively studied regarding new compositions, processing routes, phase transformation, mechanical and functional properties. Aspects of the thermoelastic phase transformation have been described using thermodynamic and thermo-mechanical studies, while the role of metallurgical features (such as grain size and morphology, ordering, precipitates and second phases) have been described mainly by phenomenological approach. In this sense this review discusses the advances in the general fundamentals of Cu-based shape memory alloys, the recent developments in processing routes, compositions, and applications in the last years. Graphical abstract

Laser Powder Bed Fusion of Cu–Al–Ni–Mn Shape‐Memory Alloy for the Application of Active Heat Sinks: Processability, Microstructures, and Shape‐Memory Effect

“…Twin martensite can be found in all samples because martensite accommodated the local strain caused by lattice change through twinning. [ 52 ] As shown in Figure 7g, with the increase of scan speed, the average size of martensite, measured from SEM images, gradually decreased from 672.7 to 495.2 nm. That is because higher scan speed resulted in shorter liquid phase time and incomplete grain growth, leading to the refinement of martensite.…”

A Review Article on FeMnAlNi Shape Memory Alloy

“…Copper based shape memory alloy is also one of the important types of shape memory alloy because of its large range of operating temperature and flexibility. It is also one of better replacement of NiTi alloy due to its less manufacturing cost (10). Despite of some advantages this copper-based alloy shows some sensitiveness to aging, transition hysteresis, phase stabilization which compresses the application of this alloy in various field (7).…”

Consolidation and properties of porous Cu–Al–Ni shape memory alloys manufactured by powder metallurgy

“…Depending on the temperature, they can attain very large strains without suffering permanent deformations due to the pseudoelastic behaviour presented by the austenite high-temperature phase [1,2]. These particular properties make these smart materials good candidates for applications involving damping or as actuators [3,4]. In particular, both Ni–Ti and Cu-based shape memory alloys are employed in commercial applications.…”