Effect of grain size on the damping capacity of quasicrystalline Al–Cu–Fe materials

Thick quasicrystalline (QC) Al–Cu–Fe coatings obtained by electron-beam physical vapour deposition (EB-PVD) on titanium substrates at different temperatures have been used for damping measurements. The measurements were performed by the method of free-decay vibrations with using flat cantilever specimens covered with the QC coatings in the strain amplitude range of 10− 4–10− 3 and in the temperature range of 290–620 K. We have studied the intrinsic damping capacity of the QC coatings with different grain sizes as a function of strain amplitude using a calculation procedure. The intrinsic damping capacity of all the QC materials is found to increase progressively with temperature in the whole strain amplitude range. It was found that decreasing of the QC grain size to nanoscale values leads to a significant increase of their damping capacity at temperatures above 520 K. Possible mechanisms of dissipation of mechanical energy in nanostructured quasicrystals at elevated temperatures are discussed.