NEW FERROMAGNETIC SHAPE MEMORY ALLOY PRODUCTION AND ACTUATOR CONCEPTS

Over the past decade ferromagnetic shape memory alloys (FSMA) have been the subject of intensive R&D work due to their potential in actuators, sensors, and intelligent systems. These smart materials can elongate and contract up to 10% when subjected to moderate magnetic fields, generating thus motion and force. Typically FSMA materials are alloys of Ni-Mn-Ga with various off-stoichiometric compositions. A new production approach based on commercially available machinery is introduced in this paper. Large single crystals have been produced demonstrating homogeneous structure and excellent magneto-mechanical properties. The properties of actuator elements (sticks) are presented as well as the influence of the alloy microstructure. The FSMA elements are used to develop prototype actuator and sensor devices for industrial and automotive applications. In this respect a benchmark between an FSMA actuator and a commercially available solenoid actuator has indicated that the FSMA technology offers potential to replace several of today's electromagnetic actuators by advanced FSMA solutions, especially when temperature requirements are met.