High damping capacity of Ni–Mn–Ga–Cu microwires prepared by melt-extraction technique

Ni–Mn–Ga–Cu microwires, with diameter of 20–80 μm, length of 30–150 mm and fined columnar grains, were produced by melt-extraction technique. The damping capacity of the extracted microwires was investigated by stretching a microwire under a tensile stress using dynamic mechanical analyzer. The damping capacity of the martensite and austenite phases shows a weak frequency dependence but a strong strain amplitude dependence. The damping capacity (Tanδ) of the martensite and austenite phases reaches 0.08 and 0.04, respectively, under strain amplitude of 0.5% and frequency of 1 Hz. The high damping capacity of the martensite phase is related to the high mobility of martensite twin boudaries, while that of austenite phase to the motion of dislocations. The ferromagnetic Ni–Mn–Ga–Cu microwires, with high ductility and damping capacity, may act as promising materials for microscale devices, systems and composite fillers for passive dissipation of undesired vibrations and noises.