Effects of Y content and temperature on the damping capacity of extruded Mg-Y sheets

Abstract

The damping behavior of extruded Mg-xY (x = 0.5, 1.0, 3.0 wt.%) sheets were investigated in detail concerning the effects of Y addition and temperature, and the relationship between damping capacity and yield strength was discussed. At room temperature (RT), with Y content increasing from 0.5% to 3.0%, the damping capacity (Q−1) significantly decreased from 0.037 to 0.015. For all the studied sheets, the relationship between strain amplitude and Q−1 fitted well with the Granato and Lücke (G-L) dislocation damping model. With temperature increased, the G-L plots deviated from linearity indicating that the dislocation damping was not the only dominate mechanism, and the grain boundary sliding (GBS) could contribute to damping capacity. Consequently, the Q−1 increased remarkably above the critical temperature, and the critical temperature increased significantly from 50 °C to 290 °C with increasing Y contents from 0 to 3.0 wt.%. This result implied that the segregation of Y solutes at grain boundary could depress the GBS, which was consistent with the recent finding of segregation tendency for rare-earth solutes. The extruded Mg-1Y sheet exhibited slightly higher yield strength (Rp0.2) and Q−1 comparing with high-damping Mg-0.6Zr at RT. At an elevated temperature of 325 °C, the Mg-1Y sheet had similar Q−1 but over 3 times larger Rp0.2 than that of the pure Mg. The present study indicated that the extruded Mg-Y based alloys exhibited promising potential for developing high-performance damping alloys, especially for the elevated-temperature application. Keywords: Extruded sheets, Mg-Y alloys, Damping capacity, Granato and Lücke model, Elevated temperature