Articles you may be interested indc-and ac-magnetic field-induced strain effects in ferromagnetic shape memory composites of Ni-Mn-Ga single crystal and polyurethane polymer J. Appl. Phys. 107, 09A942 (2010); 10.1063/1.3357408 Large magnetic-field-induced strains in Ni-Mn-Ga nonmodulated martensite Appl. Phys. Lett. 95, 104103 (2009); 10.1063/1.3227661Acoustic-assist effect on magnetic threshold field and twinning-yield stress of Ni-Mn-Ga single crystals
Ni–Mn–Ga based ferromagnetic shape memory alloys (FSMAs) have been shown to exhibit large magnetic-field-induced strain (MFIS) up to 10% for frequencies up to 1 kHz. However, a magnetic threshold field of 150–300 kA/m is typically required to achieve MFIS, which will require a large electromagnet. The application of a small acoustic signal to the FSMA crystal during MFIS has been shown to reduce the threshold field by up to 80 kA/m and increase the stress and strain outputs. We systematically study the threshold field and the twinning-yield stress of Ni–Mn–Ga single crystals with and without acoustic assist. The acoustic-assist technique helps to reduce the required threshold field and twinning-yield stress of the samples studied here by 60%. The effectiveness of the acoustic assistance in enhancing twin-boundary motion increases with increasing acoustic drive frequency up to a limiting frequency of 2–5 kHz. The magnitude of the acoustic-assist effect appears to be limited by the performance of the piezoelectric stack used in this experiment. The acoustic assistance is a result of a bipolar stress wave that enhances twin-boundary motion in either direction. For a given piezodrive frequency and displacement amplitude, the stress-wave theory provides an estimate of the expected acoustic stress-wave magnitude, and this acoustic stress value is consistent with the observed decrease in twinning-yield stress.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.