The amplitude-dependent and temperature-dependent low frequency damping capacities of magnesium with 99.96% purity were studied by a dynamic mechanical analyzer. The pure magnesium alloys include CPM1 and CPM2 casting...The amplitude-dependent and temperature-dependent low frequency damping capacities of magnesium with 99.96% purity were studied by a dynamic mechanical analyzer. The pure magnesium alloys include CPM1 and CPM2 castings having textures of columnar grains which extraordinarily influence the damping behaviours. The commercial pure magnesium alloy CPM was re-melted to obtain equiaxed grains, which could remove the effect of texture orientation on the damping behaviours of these pure magnesium alloys. The results of strain amplitude-dependent damping spectrums of these pure magnesium alloys show that the pure magnesium with equiaxed grains possesses the highest damping capacity. In temperature-dependent damping plot for all these three pure magnesium alloys, there are two damping peaks P1 and P2 located at 80 and 230 °C, respectively. These two damping peaks are considered to be caused by the interaction between dislocation and point defects, and the movement of grain boundaries, respectively.展开更多
The EPR 9 factors for cubic, tetragonal and orthorhombic Fe^＋ centers in alkali halides MX （M= Li, Na; X = F, CI） are calculated from second-order perturbation formulas of g factors based on cluster approach for 3...The EPR 9 factors for cubic, tetragonal and orthorhombic Fe^＋ centers in alkali halides MX （M= Li, Na; X = F, CI） are calculated from second-order perturbation formulas of g factors based on cluster approach for 3d^7 ions in three symmetries. From calculations, the g factors of these Fe^＋ centers in MX crystals are reasonably explained and the defect structural data for the tetragonal and orthorhombic Fe^＋ centers are estimated. The results are discussed.展开更多
基金Project (50801017) supported by the National Natural Science Foundation of Chinaproject (20080440843) supported by Postdoctoral Science Foundation, ChinaProject (HIT.NSRIF.2009028) supported by the Natural Scientific Research Innovation Foundation of Harbin Institute of Technology, China
文摘The amplitude-dependent and temperature-dependent low frequency damping capacities of magnesium with 99.96% purity were studied by a dynamic mechanical analyzer. The pure magnesium alloys include CPM1 and CPM2 castings having textures of columnar grains which extraordinarily influence the damping behaviours. The commercial pure magnesium alloy CPM was re-melted to obtain equiaxed grains, which could remove the effect of texture orientation on the damping behaviours of these pure magnesium alloys. The results of strain amplitude-dependent damping spectrums of these pure magnesium alloys show that the pure magnesium with equiaxed grains possesses the highest damping capacity. In temperature-dependent damping plot for all these three pure magnesium alloys, there are two damping peaks P1 and P2 located at 80 and 230 °C, respectively. These two damping peaks are considered to be caused by the interaction between dislocation and point defects, and the movement of grain boundaries, respectively.
基金The project supported by National Natural Science Foundation of China under Grant No. 10274054
文摘The EPR 9 factors for cubic, tetragonal and orthorhombic Fe^＋ centers in alkali halides MX （M= Li, Na; X = F, CI） are calculated from second-order perturbation formulas of g factors based on cluster approach for 3d^7 ions in three symmetries. From calculations, the g factors of these Fe^＋ centers in MX crystals are reasonably explained and the defect structural data for the tetragonal and orthorhombic Fe^＋ centers are estimated. The results are discussed.
