Mechanical spectroscopy measurements on SMA high-damping composites

High-damping materials have attracted much attention to solve problems such as acoustic pollution, nano-scale vibration isolations in electronic industry, vibration damping in civil engineering, etc. Shape memory alloys (SMAs), which intrinsically present high-damping capacity, are considered as alternative materials to the traditionally used polymeric ones, because they present better mechanical properties at moderate temperatures. A new kind of high-damping metal matrix composites has been produced by embedding a relatively high amount (approximately 60 vol.%) of Cu-Al-Ni SMA particles with metallic matrices (In, In + Sn). The damping properties have been characterized by mechanical spectroscopy, using an inverted torsion pendulum, as a function of temperature (150-400 K), frequency (0.01-3 Hz), and strain amplitude (2 × 10−5 to 8 × 10−5). The materials exhibit internal friction higher than 0.5 in a relatively wide temperature range. The ability of matching the temperature of maximum damping, through the composition of the SMA, opens new possibilities for designing high-damping materials for specific applications.