Pulsed field actuation of Ni-Mn-Ga ferromagnetic shape memory alloy single crystal

• DOI: 10.1051/jp4:20031050
• Publication Date: 2008-08-19T10:56:00Z
• Authors: M. Marioni; D. Bono; A. B. Banful; M. del Rosario; E. Rodriguez; B. W. Peterson; S. M. Allen; R. C. O'Handley
• Keywords: Magnetic shape-memory alloy; Crystal (programming language); Elongation

Ferromagnetic Shape Memory Alloy Ni-Mn-Ga has twin boundaries in the martensitic phase that move when a suitable magnetic field is applied. In this fashion strains of up to 6% have been observed for static fields in single crystals [1]. Recently 2.5% strain has been demonstrated [2] in Ni-Mn-Ga single crystals for oscillating fields up to frequencies of 75Hz (150Hz actuation). This work studies the actuation of single crystals when pulsed fields are applied. Fields in the 0.4-1.5MA/m-range were generated in an air coil with rise times of the order of 1ms and below. The elongation of the samples is measured with a light beam reflected off the tip of the crystal. Single twin boundaries have been observed to advance 0.16mm during 600μsec-long pulses. Actuation has been shown to be possible at least up to frequencies of 1700Hz.