Effect of Co on twin formation and magnetic properties of Sm(Fe,Ti,V)12 alloys

Transferring the excellent intrinsic magnetic properties of SmFe12-based compounds to their extrinsic properties remains the main challenge in the development of high-performance SmFe12-based permanent magnets. Twin formation is one of the reasons for the inability to achieve high coercivity and remanence. Here we have shown that the addition of Co in Sm(Fe1-xCox)10–11M1–2 alloys, where M=Ti and V, leads to an increase in twin density. Microstructural characterizations revealed that the atomic arrangement in the twin boundary changes depending on the stabilizing element, which directly influences the local intrinsic magnetic properties. Theoretical investigations showed that the critical grain size at which twin formation can be hindered by grain size reduction decreases when the stabilizer changes from V to Ti. This study shows that the alloy composition influences not only the intrinsic magnetic properties but also the twin formation energy and its grain size dependence, crucial for the design of SmFe12-based permanent magnets

Optimization of the magnetic properties of nanostructured Y-Co-Fe alloys for permanent magnets

The structural and magnetic properties of ball-milled Fe-doped Y Co5−xFex(0 ≤ x ≤ 0.5) were investigated. The magnetization increases with Fe-doping up to the solid solubility limit, x = 0.3 without destroying the crystal structure or degrading the coercivity. A special magnet array is designed using ring magnets for pressing the powders under magnetic field in order to achieve magnetic alignment. A dramatic increase in magnetization is observed for magnetically aligned Y Co4.8Fe0.2 pressed ingots

Optimization of the magnetic properties of nanostructured Y-Co-Fe alloys for permanent magnets

The structural and magnetic properties of ball-milled Fe-doped Y Co5−xFex(0 ≤ x ≤ 0.5) were investigated. The magnetization increases with Fe-doping up to the solid solubility limit, x = 0.3 without destroying the crystal structure or degrading the coercivity. A special magnet array is designed using ring magnets for pressing the powders under magnetic field in order to achieve magnetic alignment. A dramatic increase in magnetization is observed for magnetically aligned Y Co4.8Fe0.2 pressed ingots

Enhanced energy product in Y-Co-Fe magnets intermediate between Nd-Fe-B and ferrite

The hysteresis of ball-milled Fe-doped YCo5 powder has been optimized by controlling the temperature and time for rapid annealing under vacuum and argon. The crystallite size is only 25 nm; yet, it has been possible to field align Y(Co, Fe) powder with a 5-20 mu m grain size in a 5 T field to obtain a remanence ratio of 0.65, due to texture in the ball-milled powder. The nominal energy product of the powder is 140 kJ/m(3). A pressed magnet with 78% of theoretical density has an energy product of 65 kJ/m(3). This magnet could fill the gap between oriented ferrite (34 kJ/m(3)) and oriented Nd-Fe-B (350 kJ/m(3)). (C) 2015 AIP Publishing LLC

13-cis-retinoic acid affects oxidation and DNA damage in oxidative-positive SLE lymphocytes but may not be useful for therapy

13-cis-Retinoic acid (13-CRA), a water-soluble vitamin A analog and 5'-lipoxygenase inhibitor, was tested in vitro for effects on excess oxidative metabolism and DNA damage in mitogen-stimulated lymphocytes from patients with systemic lupus erythematosus (SLE), because other 5'-lipoxygenase enzyme inhibitors were shown to lower the excess oxidative metabolism in SLE cells. Excess chemiluminescence (CL) was abolished within minutes after the addition of 1 x 10(-6) M 13-CRA in five of five CL-positive mitogen-stimulated SLE lymphocytes, and was lowered in five of eight samples after 48 to 72 h culture. Similarly, low concentrations of 13-CRA for 48-72 h largely prevented the S1 nuclease-sensitive DNA changes/DNA damage observed in CL-positive lupus lymphocytes in vitro. However, 13-CRA did not affect DNA damage in four of four CL-negative lymphocyte samples. 13-CRA, like other retinoic acid compounds, was known to stimulate B-cell activities in vivo and in vitro but effects on dividing lupus T cells had not been studied. 13-CRA further inhibited the diminished PHA-stimulated lupus T-cell growth in tissue culture at a concentration of 9 x 10(-6) M in three of five lupus lymphocyte samples. 13-CRA has positive and negative effects on multiple aspects of the immune system and it is not clear whether 13-CRA will have positive or adverse clinical effects on SLE patients. Close attention to vitamin A and vitamin "supplements" in patients with SLE may answer this question

Enhanced energy product in Y-Co-Fe magnets intermediate between Nd-Fe-B and ferrite

The hysteresis of ball-milled Fe-doped YCo5 powder has been optimized by controlling the temperature and time for rapid annealing under vacuum and argon. The crystallite size is only 25 nm; yet, it has been possible to field align Y(Co,Fe) powder with a 5-20 μm grain size in a 5 T field to obtain a remanence ratio of 0.65, due to texture in the ball-milled powder. The nominal energy product of the powder is 140 kJ/m3. A pressed magnet with 78% of theoretical density has an energy product of 65 kJ/m3. This magnet could fill the gap between oriented ferrite (34 kJ/m3) and oriented Nd-Fe-B (350 kJ/m3)