Breaching the work output limitation of ferromagnetic shape memory alloys

Ganor, Yaniv; Shilo, Doron; Shield, Thomas W.; James, Richard D.
September 2008
Applied Physics Letters;9/22/2008, Vol. 93 Issue 12, p122509
Academic Journal
One important parameter that quantifies the performance of ferromagnetic shape memory alloys is the blocking stress. To date, the low blocking levels (<5 MPa) impede the utilization of these alloys in applications where high work output is required. In this paper, we demonstrate an increase in the blocking stress by more than 100% by reducing the actuator size. A new theoretical model shows that smaller specimens have increased values of the blocking stress due to an enhancement in the energy barrier to magnetization rotation and indicates on a fundamental relationship among the specimen size, its microstructure, and its physical properties.


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