Achieving high damping and excellent ductility of Al[sbnd]Mg alloy sheet by the coupling effect of Mg content and fine grain structure

Abstract

Fine-grained Al-xMg (x = 4.5, 6.5 and 9.2, in wt%) alloy sheets with high damping capacity and excellent ductility are prepared by high strain rate rolling (HSRR). Both the damping capacity and the mechanical properties of the alloys are improved compared with the as-homogenized states and increase with the higher Mg content. The three AlMg alloys exhibit similar strain-amplitude-independent damping capacities and the Al-9.2 Mg alloy is a little bit higher. While the strain-amplitude-dependent damping capacity increases with increasing the Mg content in a large strain amplitude range. The as-HSRRed Al-4.5 Mg, Al-6.5 Mg and Al-9.2 Mg alloys exhibit the damping values (Q−1) of 0.0140 ± 0.0005, 0.0167 ± 0.0006 and 0.0178 ± 0.0008 at the strain amplitude of 1 × 10−3. Furthermore, a combination of high ductility (42.8 ± 1.5%), moderate strength (435 ± 2 MPa) are also achieved in the Al-9.2 Mg alloy. The improved damping capacity of the as-HSRRed Al-9.2 Mg alloy are mainly attribute to the low stacking fault energy and the movement of the extended dislocation, the latter of which interaction with Suzuki atmosphere and thus increases energy consumption which plays a dominant role in the damping mechanism of the as-HSRRed alloys. The results of the present study provide new ideas for the development of high damping alloys with high mechanical property.