Terfenol-D is a type of magnetostrictive material, which means it can change shape when exposed to a magnetic field. It is made from a combination of terbium, iron, and dysprosium, and is known for its ability to produce significant mechanical movement in response to magnetic stimuli. This property makes it useful in various applications, including sensors and actuators. Due to its unique characteristics, Terfenol-D is often used in advanced technologies such as sonar systems and vibration control devices. Its ability to convert magnetic energy into mechanical energy allows for precise control in engineering and robotics, enhancing performance in many fields.