Microstructure and damping capacities of Mg-6Zn-1.5Cd-0.5Zr alloy

There are many factors affecting the damping properties of magnesium alloys. The damping capacities and microstructure of Mg-6Zn-1.5Cd-0.5Zr(abbr. MC) alloy were investigated on three different treatment states such as cast alloy, solid solution alloy and extruded alloy. The result of research shows that the average grain size of MC alloy as cast, as solution and as extrusion is 80μm, 40μm and 4-20μm, respectively. Throughout the test strain range, the strain damping capacities of MC alloy as cast is lower than that of Mg-6Zn-0.5Zr (abbr. M)alloy as cast. The length between weak pinning points on the dislocation line is reduced by Cd elements solution in the a-Mg matrix. The strain independent damping capacities (Ql-1) of MC alloy as cast equal to about 0.00108, as well as solid solution alloy and extruded alloy almost. When the strain amplitude (ε) exceeds the first critical de-pinning strain amplitude (ε1cr), the strain-dependent damping value (QH-1) of the solid solution and extruded alloys are greater than that of the cast alloy. When strains ε > 4.18×10−4, QH-1of solid solution alloy and extruded alloy reach above 0.01025 and 0.01057, respectively. In the test range, the damping capacity QH-1of MC alloy in casting state, solid solution state and extrusion state reaches the maximum value, which are 0.01201, 0.01406 and 0.01491, respectively. The damping mechanism of MC alloy accords with Granato and Lücke ( G-L) theory.