| Rare earth-cobalt alloys RCo5 (R= Y, Ce, Pr and Sm) have attracted considerable attention due to their relatively high saturation magnetizations MS, large anisotropy fields HA and high Curie temperatures TC, To possess as permanent magnet. Except sintered SmCo5, however, these alloys have not been widely used due to the technical difficulties in achieving appropriate microstructure necessary for developing high enough coercivity.Rapid quenching (melt-spun) possess is a solidification with a great cooling rate from the melt directly .which means molten ally under certain pressure and atmosphere of argon jet to the rotating water-cooled copper roll and curdle in 30 ~ 50um thick strip, getting a super-fine structure. This way of great cooling spread can make the grain size to nanometer. Also for its convenience and low energy consumption. Many researchers have fabricated melt-spun YCo5 , PrCo 5 and SmCo5 magnet, but the magnetic properties could not satisfy the practical requirements still. Recently, obvious grain orientation of melt-spun RCo5 has been reported, which makes the application of melt-spun RCo5 anisotropic bonded magnets possible. YCo 5 posses similar inherent magnetic properties as SmCo5, especially that Y is much cheaper than Sm in price due to its rich reseves, making the study on anisotropic melt-spun YCo5 permanent magnet so significant.In this work, melt-spunYCo5 ribbons have been made, and the effect of ingredient and cooling speed on gain orientation and magnetic properties have been investigated. In addition, magnetic properties of ribbons have been improved by Fe and C doping At the same time, the magnetization reversal mechanism has also been discussed and analyzed. The main activities include as following:1. Ingots with composition of YCo5.4, YCo5.0 and YCo4.6 were manufactured by arc-melting under the argon protection. R-rich phase has been found in arc-melt Y-Co alloy with the ratio of 1:5 beside YCo5 phase, which could be inhibited by increasing Co content, YCo alloy with single YCo5 phase has been obtained at the ratio of 1:5.4 finally. 3 Surface velocities (Vr) of the Cu roll have been fabricated with different roll velocities of 5m/s, 15m/s, 25m/s and 35m/s respectively. XRD studies on no-contact surface of YCo5 ribbons show that the crystal axes of sets of YCo5 ribbons prefer a certain orientation. The easy magnetization directions of samples fabricated by lower spread are prefer to arrange along the ribbon length. With the increase of speed the easy magnetization direction turn to perpendicular to the plane. The magnetic anisotropy mainly originates from the orderly arrangement of easy magnetization axes. With the increase of speed, the coercivities increased gradually, but it is impassable to apply in real word.Magnetic properties of YCo5.4 ribbons were tested along the ribbon length, ribbon width and perpendicular to the ribbon plane by Vibrating Sample Magnetometer (VSM), the results show that the direction along ribbon length is always the easy magnetization direction. Considering the results tested by XRD, we can figure out that C-axis should prefer to arrange along the ribbon length. For the ribbons spun at lower speed, the difficult magnetization direction is along the ribbon width, and for those spun at higher speed the difficult magnetization direction perpendicular to the ribbon plane, which are consistent with the conversion to the direction parallel the ribbon plane from along the ribbon length tested by XRD. Coercivities measured along easy axes are smaller than that along the hard axes, indicating that the coactivity mechanism accords with the model of domain wall pinning. At even high wheel speed, both X-RAD and magnetic measurement showed that the ribbons tend to be isotropic.2. Substituted Fe for partial Co, YCo4.9Fe0.5, YCo4.4Fe1.0 and YCo3.9Fe1.5 ribbons were prepared with =5 m/s, 15m/s, 25m/s and 35m/s. The crystalline and magnetic anisotropy are still exist and the change rules are similar to that of ribbons without Fe substitution, namely the C-axes is parallel to the ribbon plane at low wheel speed and perpendicular to the plane at high wheel speed. At even high speed the crystalline texture and magnetic anisotropy are getting vanished gradually. Due the substitution of Fe, the coercivity drop and the magnetion increase pronouncedly. v3. In order to refine the microstructure and improved the permanent magnetic properties, C is doped in YCo 5 ribbons. Ribbon's compositions are YCo5.4C0.2, YCo5.4C0.4 and YCo5.4C0.6. There are still magnetism anisotropy after the C doping, but only exists in the sample with low quenching velocity and already weakened. We extrapolated that the C doping has suppressed the sample's anisotropy. Coercivities rise obviously for all samples, and there appear an optimal wheel speed at which the coercive reach its maximum value. For a more detailed study, we further refine the rejection with the speed, the speed was 5m/s, 10m/s, 15m/s, 20m/s, 25m/s, 30m/s and 35m/s. Components YCo5.4 samples, band rejection rate for the 35m/s when the maximum coercivity, YCo5.4C0.2 samples, with the best velocity of 25m/s, the coercivity reaches the maximum, Components YCo5.4C0.4 samples, with the best velocity of 20m/s, the coercivity reaches the maximum and Components YCo5.4C0.6 samples, with the best velocity of 15m/s, the coercivity reaches the maximum. increase the coercivity of the sample is also rapidly increasing energy product, (BH)max reaches 7.33MGOe if density of 7590kg/m3 is adopted. We also calculated the unit cell volume of samples YCo5.4(35m/s), YCo5.4C0.2(25m/s), YCo5.4C0.4(20m/s), YCo5.4C0.6 (15m/s). Found with the C content increased, a gradual decreases, c increases, the total volume v decreases. From this we can infer that after doping C increase in coercivity is due to grain refinement of the results, because the coercivity is closely related with the grain size, the grain smaller, the grain exchange coupling stronger between grain. The C content has an optimal value of 0.4, at which the largest coercivity and the magnetic energy product have been obtained.
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