Crystallization, morphology and magnetic properties of melt-spun (Nd,Pr,Dy)/sub 2/(Fe,Co,Mo)/sub 14/B//spl alpha/-Fe nanocomposites
Crystallization, phase evolution, nanostructure, exchange coupling, and hard magnetic properties of melt-spun Nd/sub 2.4/Pr/sub 5.6/Dy/sub 1/Fe/sub 85/B/sub 6/ and Nd/sub 2.4/Pr/sub 5.6/Dy/sub 1/Fe/sub 78/Co/sub 6/Mo/sub 1/B/sub 6/ nanocomposites have been studied. All the Nd/sub 2.4/Pr/sub 5.6/Dy/sub 1/Fe/sub 85/B/sub 6/ alloys annealed for 30 s at 565/spl deg/C or above contain nanostructured /spl alpha/-Fe and Nd/sub 2/Fe/sub 14/B-type (2:14:1) phases, whereas Nd/sub 2.4/Pr/sub 5.6/Dy/sub 1/Fe/sub 78/Co/sub 6/Mo/sub 1/B/sub 6/ alloys annealed at 600/spl deg/C or below are mainly composed of /spl alpha/-Fe and a metastable 1:7 phase. A small amount of 2:14:1 phase forms after annealing at 600/spl deg/C. When annealed at 640/spl deg/C or above, the hard phase in Nd/sub 2.4/Pr/sub 5.6/Dy/sub 1/Fe/sub 78/Co/sub 6/Mo/sub 1/B/sub 6/ alloys is the 2:14:1 phase rather than the 1:7 phase. The differences in magnetic properties of the Nd/sub 2.4/Pr/sub 5.6/Dy/sub 1/Fe/sub 85/B/sub 6/ and Nd/sub 2.4/Pr/sub 5.6/Dy/sub 1/Fe/sub 78/Co/sub 6/Mo/sub 1/B/sub 6/ nanocomposites at different anneal temperatures result from the different nanostructures, exchange coupling and phase components present in the alloys, in particular from the different amount of the 1:7 phase.
High anisotropy Nd(Fe,T)12Nx, T=Ti, Mo films and disordered RE(FE,Ti) phases before and after nitriding
Highly textured thin films, of ordered Nd(Fe,T)12, T=Ti, Mo, and disordered Nd(Fe,Ti)7 phases, were synthesized by rf sputter deposition. The 1–12 films were highly (002) textured with the c axes oriented perpendicular to the film plane. The disordered Nd‐Fe‐Ti films were fitted to the disordered TbCu7 phase and could be made highly (110) textured with the c axes randomly distributed in the film plane. Nitriding was carried out in N2 at P=400 Torr at ≊450 °C for 2 h. The room‐temperature magnetocrystalline anisotropy fields of the NdFe11Ti and NdFe11Mo films, which were uniaxial, were 10 and 5 kOe, respectively. After nitriding the NdFe11TNx films remained uniaxial, but the anistropy fields increased to 108 and 130 kOe for Ti and Mo, respectively. The iHc perpendicular to the film plane of NdFe11T increased to 5.3 kOe, T=Ti, and to 7.2 kOe, T=Mo, after nitriding. At 293 K, the highest‐energy product of 30.2 MGOe was obtained for a T=Mo nitrided sample. The hysteresis loops of disordered Nd(Fe,Ti)7 and Nd(...
An analytical approach to the design of electrodes in high-power, fast-transverse-flow CO2 lasers
Abstract Usually, the design of the electrodes of fast-transverse-flow CO 2 lasers relies more on experimental data than on theoretical analysis. Traditional systems sustain a stable, high-power discharge but the current distribution generates a peaked, non-uniform small-signal-gain pattern. We present a theoretical model suitable for the design of electrodes that achieves a quasi uniform gain distribution. The analysis, based on a two-temperature model and the gas-transport equations, computes the electron density that supports a flat gain pattern. Combining the desired electron density with the electron-balance equations, the model determines the required electric field. The results were used to design a new set of electrodes for a home-made fast transverse flow CO 2 laser. A stable, large volume discharge ( 4 × 8 × 90 cm 3 ) with very good uniformity was obtained. The resulting gain distribution was registered in a bi-dimensional map. The peak gain rose from 1.2 m - 1 , attained with the old electrode set, to 1.6 m - 1 with the new one and the gain showed a homogeneous profile.