Improved damping behavior of squeeze-cast AZ91-Ca-Sb magnesium alloy with nano-SiC particles additions

Abstract

The damping behavior of the SiCnp reinforced AZ91 + 2.0Ca+ 0.3Sb (wt%) alloy in the temperature range of 25–350 °C and at frequencies of 1, 5, and 10 Hz has been evaluated. All the AZ91 + 2.0Ca+ 0.3Sb+xSiCnp [x = 0.5, 1.0, and 2.0 (wt%)] nanocomposites exhibit higher storage modulus, loss modulus, and damping capacity than the alloy. The storage modulus decreases with an increase in temperature and frequency, whereas the loss modulus and damping capacity increase with an increase in temperature and decrease with frequency. The nanocomposites display a higher dislocation density and activation energy than the alloy, and the values are the maximum in the nanocomposite with 2.0SiCnp. The higher damping response of the nanocomposites is due to the presence of nano-SiC particles, higher storage and loss moduli, higher activation energy, and increased dislocation density. The Granato-Lucke mechanism, grain boundary or viscous damping, and dislocation damping are the operative damping mechanisms in the alloy and all the nanocomposites.