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近20年来,稀土永磁材料的开拓及其发展经历了三代,即第一代RCo_5型(1966年),第二代R_2Co_(17)型(1972年)和第三代Nd-Fe-B系(1983年)永磁合金(R为稀土或混合稀土族元素)。永磁合金的最大磁能积(BH)_(max)随年代呈指数式增加。早就发现的R_2Fe_(17)居里温度太低,而且Nd_2Fe_(17)还缺少必要的磁晶各向异性。这些性质限制了它的发展。但在其中添加B后,稳定了四方结构,显示出易磁化轴各向异性和较高的居里点(580K。自此,第三代稀土永磁体发展起来了。1983年日本正式公布了无钻、高性能的新型Nd-Fe-B永磁体,最大磁能积达到36.3MGOe;1984年达到42.9MGOe,1985年达到44.8MGOe。目前日本最大磁能积已突破50MGOe,并达到50.6MGOe的最高水平。
In the recent 20 years, the development and development of rare earth permanent magnetic materials have undergone three generations: the first generation RCo_5 (1966), the second generation R_2Co_ (17) (1972) and the third generation Nd-Fe-B (1983) permanent magnet alloys (R is rare earth or mixed rare earth elements). The maximum energy product (BH) _ (max) of permanent magnet alloys increases exponentially with age. It has been found that the Curie temperature of R 2 Fe 17 is too low, and Nd 2 Fe 17 also lacks the necessary magnetocrystalline anisotropy. These properties have limited its development. However, after the addition of B, the tetragonal structure was stabilized, exhibiting an easy axis anisotropy and a high Curie point (580 K. Since then, the third generation of rare earth permanent magnets has developed.) In 1983, Japan officially announced the absence of The new high-performance Nd-Fe-B permanent magnet with a maximum energy product of 36.3MGOe reached 42.9MGOe in 1984 and reached 44.8MGOe in 1985. At present, the maximum energy product in Japan has exceeded 50MGOe and reached the highest level of 50.6MGOe.