烧结NdFeB的铸锭组织分析

Analysis on the Microstructures of Cast Ingots for Sintered NdFeB Magnets

影响NdFeB磁性能的主要因素包括成分和生产工艺。本文研究了不同铸锭制备工艺获得的铸锭组织。研究发现,柱状铜模浇铸出的铸锭片状晶发达,表面和中心晶粒差异较大。而板状铁模浇铸出的铸锭虽然析出了大量α-Fe,但同时又使铸锭的晶粒细化,均匀性好,晶粒尺寸细化到了20μm,富钕相分布均匀;α-Fe在气流磨的吐料过程中大部分被排除,烧结体的晶粒细化到约10μm;磁体的磁能积达到了336kJ/m3(42MGOe)。

The composition and production process have an important effect on NdFeB magnetic properties. The ingots cast by different mold (cylindrical copper mold and plate iron mold) had been studied in this article. The results indicate that the former consists of large and uniformless grains and the latter consists of fine and uniform grains. The microstructure of ingots cast by plate iron mold, despite the α-Fe separated out, is refined to 20μm and Nd-rich phase is well-distributed. α-Fe is eliminated during jet milling process. The microstructure of the sintered magnet was refined to 10μm and the magnetic energy product of 336kJ/m3(42MGOe) was achieved.