Damping properties of ductile Cu-Al-Mn-based shape memory alloys

The damping property tan φ of Cu-Al-Mn-based alloys, where tan φ is nearly equal to internal friction Q ^-1, was investigated using a Dynamic Mechanical Spectrometer (DMS). It was found that the dependences of frequency and strain amplitude on tan φ are significantly different between the parent + martensite two-phase and the martensite single-phase states, i.e., tan φ is mainly influenced by frequency in the two-phase state and by strain amplitude in the martensite state. It was also found that the relative grain size d/D is a function of the damping capacity, where d and D are the grain diameter and the diameter of the wire, respectively, and that tan φ increases with increasing d/D. The maximum values of tan φ = 0.54 and tan φ = 0.07 were obtained in the two-phase state and in the martensite state, respectively, in the specimen of d/D ≈ 1.