Search

The CoFe-based amorphous and Fe-based nanocrystalline alloys possess excellent soft magnetic properties due to their nearly zero-magnetostriction and very low magnetic anisotropy. So they are good candidate materials for power electronics and giant magneto-impedance (GMI) sensor applications. As an indication of their AC performance, energy losses were determined by the measurements of impedance for Co68.2Fe4.3Si12.5B15 amorphous wire and Fe73.5Cu1Nb3Si13.5B9 nanocrystalline wires with different domain structure. The measurements were carried out at a frequency range of 10 – 104 Hz and induction amplitudes of 0.1 – 1.2 T. Although the measured results show good agreement with the scale theory model of energy loss, different origins of energy loss in the investigated samples have been concluded by comparing the experimental data with the Bertotti’s statistical model. The differences of energy loss in these samples could be explained by considering the magnetic structure and circular technical magnetization processes.

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.

Sr3Al2O6:Ce3+ powders were synthesized using a solid state reaction method in air with addition of H3BO3. The effects of Ce3+ dopant concentrations and the weight ratio (wt) of H3BO3 to total raw materials weight on the formation of Sr3Al2O6:Ce3+ samples were investigated. Single-phase and well-crystallized Sr3Al2O6:Ce3+ samples can be obtained when the addition of H3BO3 is lower than 7 wt%. The excitation spectrum indicates that Sr3Al2O6:Ce3+ phosphor powders exhibit two excitation bands centered at 345 and 462 nm. The emission spectrum shows that Sr3Al2O6:Ce3+ phosphor powders exhibit an emission band peaked at 536 nm when excited at 462 nm. Sr3Al2O6:Ce3+ sample at the Ce3+ concentration of 5 mol% shows the strongest emission intensity. The addition of H3BO3 has obvious influence on phase and emission intensity of Sr3Al2O6:Ce3+ phosphors. The results show that the Sr2.95Ce0.05Al2O6 sample with the 7 wt% addition of H3BO3 has the highest emission intensity and the longest lifetime.