Santosh S, Harris W B Jefrin, Srivatsan T S
Department of Mechanical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Chennai 603110, India.
Department of Mechanical Engineering, The University of Akron, Akron, OH 44325, USA.
Materials (Basel). 2023 Aug 17;16(16):5660. doi: 10.3390/ma16165660.
Shape memory effects coupled with superelasticity are the distinctive characteristics of shape memory alloys (SMAs), a type of metal. When these alloys are subject to thermomechanical processing, they have the inherent ability to react to stimuli, such as heat. As a result, these alloys have established their usefulness in a variety of fields and have in recent years been chosen for use in stents, sensors, actuators, and several other forms of life-saving medical equipment. When it comes to the shape memory materials, nickel-titanium (Ni-Ti) alloys are in the forefront and have been chosen for use in a spectrum of demanding applications. As shape memory alloys (SMAs) are chosen for use in critical environments, such as blood streams (arteries and veins), orthodontic applications, orthopedic implants, and high temperature surroundings, such as actuators in aircraft engines, the phenomenon of environment-induced degradation is of both interest and concern. Hence, the environment-induced degradation behavior of the shape memory alloys (SMAs) needs to be studied to find viable ways to improve their resistance to an aggressive environment. The degradation that occurs upon exposure to an aggressive environment is often referred to as corrosion. Environment-induced degradation, or corrosion, being an unavoidable factor, certain techniques can be used for the purpose of enhancing the degradation resistance of shape memory alloys (SMAs). In this paper, we present and discuss the specific role of microstructure and contribution of environment to the degradation behavior of shape memory alloys (SMAs) while concurrently providing methods to resist both the development and growth of the degradation caused by the environment.
形状记忆效应与超弹性相结合是形状记忆合金（SMA）这种金属类型的独特特性。当这些合金经过热机械加工时，它们具有对热等刺激做出反应的内在能力。因此，这些合金在各种领域都已证明了其用途，并且近年来已被选用于支架、传感器、致动器以及其他几种形式的救生医疗设备中。在形状记忆材料方面，镍钛（Ni-Ti）合金处于前沿，并已被选用于一系列要求苛刻的应用中。由于形状记忆合金（SMA）被选用于关键环境中，如血流（动脉和静脉）、正畸应用、骨科植入物以及高温环境，如飞机发动机中的致动器，环境诱导降解现象既受到关注也令人担忧。因此，需要研究形状记忆合金（SMA）的环境诱导降解行为，以找到提高其对侵蚀性环境抗性的可行方法。暴露于侵蚀性环境时发生的降解通常称为腐蚀。环境诱导降解或腐蚀是一个不可避免的因素，可以使用某些技术来提高形状记忆合金（SMA）的抗降解性。在本文中，我们展示并讨论了微观结构的具体作用以及环境对形状记忆合金（SMA）降解行为的影响，同时提供了抵抗环境引起的降解的发展和增长的方法。
