A Critical Review on Nickel–Titanium Thin-Film Shape Memory Alloy Fabricated by Magnetron Sputtering and Influence of Process Parameters

Abstract

This paper discussed the fundamentals of NiTi shape memory alloy and its applications in advanced scientific fields. Currently, the world is focusing on miniaturized systems for various industrial and functional applications. The thin-film shape memory NiTi alloy plays a crucial role in MEMS/NEMS industry in fabrication of microdevices. In this article, the NiTi phase diagram along with the shape memory effect and superelasticity has also been explained. Among several types of fabrication techniques for NiTi thin films, magnetron sputtering, which yields a better homogeneous film, has been discussed. Both the operational parameters (target type, Ar pressure, applied power, target-substrate distance, substrate rotation, substrate temperature, plasma stability, deposition rate) and the material's parameters (deposition pattern, orientation of adatom, film thickness, film stress, crystal structure, grain size, intermetallic formation, oxide formation, phase transformation) have been correlated in this article. The utilization of shape memory behavior in various industrial applications has been discussed here, also the advantages and limitations of SMA have been briefly discussed.

Exploring the Influence of the Deposition Parameters on the Properties of NiTi Shape Memory Alloy Films with High Nickel Content

“…The heattreatment temperature is critical since, if low, it might not be enough to fully crystallize the films. On the other hand, a temperature higher than necessary can promote the precipitation of undesired phases, such as NiTi 2 , Ni 3 Ti, and oxides, which can influence the films' phase transformation temperatures, as well as the mechanical properties [7,15]. In addition, the mechanical properties are also influenced by grain growth during the heat treatment.…”

Cryo treatment and corrosion studies of nickel-titanium shape-memory alloy

“…The effective stimulus is either in the form of heat generated by thermal energy or electrical energy or by the application of loads through which phase transformation occurs to recover the shape. [1][2][3][4][5] The widely used SMA is a nickel (Ni)-titanium (Ti) alloy popularly known as Nitinol. As of today, NiTi SMA is found to be applied in electrical, mechanical, and medical fields in the form of actuators, valves, couplings, sensing devices, lifting devices, auto switch, etc.…”

Thermal Stability of Cu-Al-Ni Shape Memory Alloy Thin Films Obtained by Nanometer Multilayer Deposition

“…Most of the works on this topic have been carried out on TiNi SMA [ 17 ], and thin films of this alloy have been produced by a variety of techniques. DC sputtering deposition [ 19 , 20 , 21 , 22 ] and RF magnetron sputtering [ 23 , 24 , 25 ] have been the most used techniques, and were recently reviewed [ 26 , 27 ]. However, other techniques are also used, such as co-evaporation [ 28 ], pulsed laser deposition [ 29 ] and e-beam evaporation [ 30 ].…”

“…High-throughput combinatorial thin films production [ 31 , 32 ] was developed to optimize the required concentration in ternary and quaternary alloys based on the TiNi system [ 33 , 34 ]. In contrast to the hundreds of publications on TiNi SMA thin films [ 17 , 18 , 26 , 27 ], only a few works have been devoted to producing and characterizing Cu-based SMA thin films [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. Nevertheless, recent studies have shown that at the micro- and nanoscales [ 44 , 45 ], Cu-Al-Ni SMA exhibits shape memory and superelastic behavior superior to those of Ti-Ni, with excellent cycling behavior at these small scales [ 46 ].…”