Introduction to Shape Memory Alloys

Abstract

Classical materials like metals and alloys have played a significant role as structural materials for many centuries [1]. Engineers have designed components and selected alloys by employing the classical engineering approach of understanding the macroscopic properties of the material and selecting the appropriate one to match the desired functionality based on the application [2]. With advancements in material science and with increasing space and logistical limitations, scientists have been constantly developing high performing materials for various applications [2]. The everlasting goal for engineers in many cases is to improve product efficiency and reduce its weight without comprising on either its cost or performance. To achieve this goal, replacing multi-component and multi-material systems with fewer multifunctional light weight, high performing materials has been an attractive alternative [2,3]. Such advanced materials have played a leading role in the development of many engineering innovations and achievements like the Airbus A380, Boeing 787 Dreamliner, reliable fuel efficient cars, superior drug delivery devices, and so on, to list a few. The ingenious commercial products across various engineering disciplines are meeting all requirements by encompassing many of the latest technologies and meeting the challenges of tomorrow's needs.In pursuit of this, material scientists over the last few decades have focused on the possibility of tailoring the microstructure of the material to generate the required functionality for different applications [2,4]. Such an effort has resulted in an entire new area of active or multifunctional materials that posses more than one desirable property [5,6]. With the introduction of such materials, researchers are now focusing on how the combined microstructural changes of such materials are able to perform multiple functions. The integration of multiple functions like actuation, sensing, and control into a single structure using one or more material constituent is seen as a possibility [2,3]. Mamoda in her recent review of future materials discusses some application ideas with such materials like: a smart solar panel that can change its orientation automatically during the day depending on sun's position; a smart shock

Photo-electrical Characterization of New CuAlNi/n-Si/Al Schottky Photodiode Fabricated by Coating Thin-Film Smart Material

“…Shape memory alloys (SMAs) are a unique smart materials group which have been extensively studied and are ever-increasingly used in many technological and industrial applications [1][2][3][4][5][6][7][8][9][10][11] today due to the shape memory effect (SME) and superelasticity (SE) properties [2] of these highly functional smart alloys. SME is a shape remembering or strain recovery mechanism that occurs as a macroscopic geometric shape change of a SMA when its temperature is changed after mechanically deformed.…”

The machining characteristics and surface integrity of Ni-rich NiTi shape memory alloy using wire electric discharge machining

“…1–5 Ni-rich SMAs are being widely used in various areas, namely robotics, biomedical, aerospace, and other important industries due to their outstanding properties. 6–9 Nevertheless, conventional machining of SMAs is extremely difficult, which creates low surface quality, high machining time, and high dimensional deviation. Therefore, to overcome these defects, the advanced machining process such as electrochemical machining, laser machining, water jet machining, electric discharge machining, and wire electric discharge machining (WEDM) process can be utilized for efficient and economic machining of SMAs.…”

Parametric study on the recast layer during EDWC of a Ni-rich NiTi shape memory alloy

“…Because of its high corrosion resistance, biocompatibility, superelasticity and shape memory effect, SMAs have been extensively used in aerospace, robotics, biomedical and other important industries. 2 – 4 However, conventional machining of SMAs is an extremely challenging task due to superelasticity and strain hardening. 5 , 6 To overcome the difficulties in conventional machining of SMAs, non-conventional machining processes such as laser machining, electrochemical machining and wire electric discharge machining (WEDM) can be exploited for machining SMAs.…”