Microstructure, mechanical properties and damping capacity of heat-treated Mg-Zn-Y-Nd-Zr alloy

The effects of solution treatment and aging on microstructure, mechanical properties and damping capacity of as-cast Mg-3%Zn-0.9%Y-0.6%Nd-0.6%Zr (wt%) (ZW30N) magnesium alloy were investigated. The as-cast alloy is comprised of α-Mg matrix and W-phase. After solution treatment at 540 °C for 8 h, the net-like interdendritic W-phase dissolves into the matrix and small Zr-containing particles precipitate at grain interiors. Due to the precipitation of fine W, β1′ and β2′ phases during the subsequent aging treatment, the ultimate tensile strength, yield strength and elongation of the alloy significantly improved from 180 MPa, 119 MPa and 12.3% in as-cast alloy to 262 MPa, 161 MPa and 15.2%, respectively. The damping capacity of heat-treated Mg-Zn-Y-Nd-Zr alloys decreases dramatically with respect to that of as-cast condition. In the solution-treated alloy, increasing number of Zr-containing particles and solute atoms in the matrix is responsible for the damping decline. For the peaked-aged alloy, the favorable damping and unusual damping growth at high strain amplitude stage are believed to be closely related to the formation of a twin dislocation, which produces new energy-dissipation source besides dislocation damping.