The Investigation Of Anisotropic NdFeB Powder

The modern industry has developed more and more fast, electrification revolution and informazation revolution took place one by one, so high-performance bonded NdFeB magnets become more and more important in modern industry. Disposed cast NdFeB alloy by HDDR, we could obtain anisotropic NdFeB magnetic powder which prepared for bonded magnets. Magnetic powder by HDDR has uniform performance, and HDDR is a simple and cheap process.We designed four contents:Nd12.5FebalCo15B6.5Zr0.5Gax (X=0,0.25,0.5,0.75), Nd12.2FebalCo15B6.0Ga0.6VY(Y=0,0.1,0.3,0.5) Nd11.5Dy1.0FebalCo15Ga0.3B6.5ZrZ(Z=0,0.1,0.2,0.3), and Nd12.5Dy10FebalCoMB6.5Zr0.1(M=14,15,16,17). The magnetic properties were measured by magnetometer. We studied different technologies of HDDR used on anisotropic bonded Nd-Fe-B magnets. The influences of Ga, Zr,V and Co contents on the magnetic properties of NdFeB alloy were also studied in this thesis. The XRD Patterns were studied by using X-ray diffraetion. The main results are as follows:1. The grain was refined by HDDR process. After HD process, the original cast structure Nd2Fe14B Phase was firstly decomposed into NdH2, α-(Fe,Co) and (Fe,Co)2B; and after the HDDR process, the three phases recombinated into NdaFe14B.2. The additional element Ga can help to improve magnetic performance and anisotropy of Nd12.5FebalCo15B6.5Zr0.5Gax, When the following process is taken:25℃×0.1MPa×1hâ†'820℃×0.03MPa×2.5hâ†'820℃×low vacuum×15minâ†'820℃×high vacuum×15min, and when the content reached0.5percentages, the permanent magnetic properties of can reach:(BH)m=222.8kJ/m3, Br=1.251T, jHc=656.8kA/m, DOA=0.523.3. The additional element V is helpful for the improvement of magnetic performance and anisotropy, and when the content reached0.3percentages the properties are best. When the following process is taken:25℃×0.1MPa×1hâ†'820℃×0.03MPa×2.75hâ†'820℃×low vacuum×15minâ†'820℃×high vacuum×15min, the permanent magnetic properties of Nd12.2FebalCo15B6.0Ga0.5VY can reach:(BH)m=155.76kJ/m3, Br=1.244T, jHc=406.4kA/m, DOA=0.496.4. The addition of less Zr can advance the alloy’s magnetic performance, and when the content reaches1percentage the properties are best. When the following HDDR technique is taken:25℃×0.1MPa×1hâ†'82℃×0.03MPa×3hâ†'820℃×low vacuum×15minâ†'820℃×high vacuum×15min, the permanent magnetic properties of Nd11.5Dy1.0FebalCo15Ga0.3B6.5ZrZ can reach:(BH)m=146kJ/m3, Br=1.243T, jHc=151.2kA/m, DOA=0.396.5The additional element Co is helpful for the anisotropy’s improvement, and when content of Co reaches15percentages,the properties are best. When the next process is taken:25℃×0.1MPa×1hâ†'820℃×0.02MPa×3hâ†'830℃×low vacuum×15minâ†'830℃×high vacuumx15min, the magnetic properties of alloy can reach:(BH)m=115.84kJ/m3, Br=1.096T, jHc=269.6kA/m, DOA=0.432.