Introduction
Shape memory alloys (SMA) are a type of alloy that is capable of returning from a deformed shape to its original shape, when an external stimuli, such as heat or stress, is applied. This is referred to as ‘shape memory effect’. The potential for shape memory alloys to be used in a range of applications has been a great interest for researchers and scientists, due to the incredible nature of the alloy. As a result, the need to become knowledgeable in the behaviour of this alloy has been birthed as a result of wanting to minimise and efficiently control such behaviour.
In this article, we will provide a discussion of the history and development of shape memory alloys, their use and application, and their behaviour when subjected to environmental factors, such as physical and chemical conditions. We will also provide an overview of shape memory alloys, including their fatigue and creep resistance, the proprioceptive capabilities, and the impact of temperature on the alloy.
History and development
Shape memory alloys were developed in the 1950s and have been used for a range of purposes since then. The first type of alloy used was a nickel titanium alloy known as Nitinol, which stands for Nickel Titanium Navy Ordnance Laboratory, after the laboratory where it was developed. This alloy was initially developed for use in the aerospace industry, and it is still used today for a variety of purposes.
Since the development of Nitinol, a range of other alloys have been developed. These include copper based alloys, iron based alloys and other titanium alloys. Each of these alloys has their own characteristics and
behaviour, which makes them more suitable for particular applications.
Use and application
Shape memory alloys have been used in a variety of applications. The most common applications include healthcare and medical uses such as orthodontic braces, prosthetics and implants; automotive applications such as gear shift level systems and dampers; and industrial applications such as actuators and connectors.
Shape memory alloys are particularly well-suited for medical applications because they are able to reduce human effort and accurately control the shape in the required manner. For example, they can be used in orthodontic braces to make adjustments in the shape of teeth easier and faster. They can also be used as connectors to join two parts together easily and quickly.
Behaviour in environmental conditions
When exposed to certain environmental conditions, shape memory alloys can demonstrate strange behaviour. For example, when exposed to temperature changes, mechanical stress, or chemical stress, these alloys can experience a change in their shape memory effect. This change can be desirable or undesirable, depending on the application and usage.
The behaviour of the alloy when exposed to environmental stress can vary depending on the particular alloy and its composition. For example, some alloys may be more temperature sensitive, while others may be more prone to mechanical stress.
Creep and fatigue resistance
When subjected to certain environmental conditions, shape memory alloys are capable of recovering from the applied shape changes (known as creep or fatigue). This can be beneficial for applications where the alloy needs to stay in a certain shape for extended periods of time.
In addition, shape memory alloys are highly corrosion resistant, which means they can withstand harsh environments, such as those found in the ocean or extreme climates.
Proprioceptive properties
Shape memory alloys are also known for their proprioceptive properties, which means they can sense the environment and provide real-time feedback to the user. This can be particularly beneficial in applications where the user needs to know the exact position of the alloy, such as in orthopedic braces.
Temperature
Finally, when it comes to shape memory effect, temperature plays an important role. The temperature of the alloy directly affects the activation temperature at which the shape memory effect occurs. Generally, the higher the temperature, the lower the activation temperature and vice versa.
Conclusion
Shape memory alloys have been used in a variety of applications, due to their remarkable behaviour when exposed to environmental conditions. They are capable of returning from a deformed shape to their original shape, when an external stimuli is applied. In addition, they have excellent fatigue and creep resistance, making them suitable for extended periods of use. They also have proprioceptive properties, meaning they can sense changes in the environment and provide real-time feedback, which can be beneficial for certain applications. Finally, the temperature of the alloy directly affects the activation temperature at which the shape memory effect occurs.
In this article, we provided an overview of shape memory alloys, their history and development, their uses and application, their behaviour when subjected to environmental factors, their fatigue and creep resistance, the proprioceptive capabilities, and the impact of temperature on the alloy. This article has hopefully provided the reader with a deeper understanding and appreciation of the capabilities of shape memory alloys.
