| Double-phase nanocomposite permanent magnets have recently been attracting considerable attention as a new permanent magnets. Nowadays, Nd-Fe-B permanent magnetic materials are widely used not only in modern science and technology, but also in the informational industries. This type of alloys simultaneously has both the advantages of hard magnetic phase's high magnetocrystalline anisotropy and soft magnetic phase's high saturation magnetization, moreover, excellent magnetic properties could be obtained by exchanging coupled interaction on a scale of the order nm.In this paper, melt-spun and crystallization treatment were used to study and prepare nanocomposite permanent magnet. The effects law of alloy composition, rapid quenching technique, crystallization treatment teperature and time on the magnetic properties of Nd2Fe14B/a-Fe type dual-phase nano-cryatal composite magnets were studied. Concrete experimental procedure is composed of bunden, melting, melt-spun, DSC, crystallization treatment, detection of magnetic properties, and phase analysis. Prepared materials were melt in vacuum arc melting-furnace first, Then poured melting master alloy into vacuum melt-spun furnace to get rapid quenching strips and chips, which were grinded into powder and detected by DSC to determine crystallization treatment technique.And then quickly quenched powder sealed in furnace and using argon gas for protection, insulation at a certain temperature after a certain period of time, out of water quenching. After cooling,using PM32-high magnetic field pulse measurement to measur the magnetic characteristics of the sample and the results were analyzed as following.Rapid quenching speed has large effedt on alloy ribbon, non-alloyed grains have grown to big size and low magnetic properties are showed when rapid quenching speed is too low. Grains become fine as the roll speed increases, followed by the improvement of magnetic properties. The alloy becomes partially or completely amorphous, which leads to the rapid decline of the magnetic properties.Cr add to.appropriatethe can effectively improve the comprehensive Magnetic Properties of the double-phase nanocomposite permanent magnets, but when Cr content is low,the influence is too weak even a minor role in side effects,When Cr content over time due to the increase of non-magnetic second phase would reduce the magnetic properties.The results of the Nd8.5Fe77.5-xCo8CrxB6 show that the optimal composition for Nd8.5Fe76.5Co8CrB6.adding Zr can increase the amount of the integrated magnetic properties of alloy. Zr can make the grain refinement to improve coercive force, but the remanence is a large degree of decline.the study of the Nd9Fe79.3-xCo5ZrxB6.5Ga0.2 show that the optimal composition is Nd9Fe78.3Co5ZrB6.5Ga0.2.In this paper, the best magnetic properties of Nd8Fe87B5 alloy obtained by directly rapid quenching occurs at roll speed of 35m/s, Br=0.842T, jHc=356.8kA/m, (BH)m=57.36kJ/m3; Specimens after crystallization treatment gets the best magnetic properties with roll speed is 45m/s, crystallization treatment temperature of 690℃and crystallization treatment time of 10min, Br=0.904T, jHc=360kA/m, (BH)m=70.96kJ/m3.Nd8.5Fe76.5Co8CrB6 alloy become optimumat 760℃for 15 min,Br=0.823T, jHc=217.6kA/m,(BH)m=47.76kJ/m3Nd9Fe78.3Co5ZrB6.5Ga0.2 alloy reaches the optimum state at 630℃for 20 min, Br=0.8T,jHc=261.6kA/m,(BH)m=51.36kJ/m3. |
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