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本文用X射线衍射、热学分析、磁性测量等手段研究了Nd-Fe-B(B≤50at.％)三元系相图,主要结果如下:1.重新测定了Nd-Fe二元系相图,确证NdFe_2相是不存在的。2.测定了Nd-Fe-B(B≤50at.％)三元系室温横截面。在该三元系中存在三个化合物:Nd_2Fe_(14)B,Nd_8Fe_(27)B_(24),Nd_2FeB_3。 指出:在未经退火的Nd-Fe-B三元母合金中,存在有过冷液相(非晶)的可能性。实用Nd-Fe-B新型永磁合金,由三相构成,主相为Nd_2Fe_(14)B,次相为Nd和Nd_8Fe_(27)B_(24)。3.测定了Fe_(94)B_6-Nd_(12)Fe_(82)B_6-Nd_(33.5)Fe_(60.5)B_6和Nd_2Fe_(17)-Nd_2Fe_(14)B-Nd_8Fe_(27)B_(24)纵截面。指出:在制备Nd-Fe-B三元永磁合金时,最高烧结温度不得高于1100℃,而后热处理的温度在600℃左右为宜。4.研究了Nd_2Fe_(14)B,Nd_8Fe_(27)B_(24)的结构和Nd_2Fe_(14)B的单相区。Nd_2Fe_(14)B为四方晶系,a=8.800,c=12.190,z=4,空间群为P4_2/mnm,X射线密度D_X=7.60g/cm~3,测量密度D_O=7.50g/cm~3。在测量精度范围内,观测不到Nd_2Fe_(14)B有单相区存在。Nd_8Fe_(27)B_(24)为四方晶系,a=7.12,c=27.40,z=2,D_X=7.01g/cm~3,D_O=7.00g/cm~3,可能的空间群为P4_2/n。5.在实验的基础上,讨论了Nd_2Fe_(14)B的热稳定性,并对制备Nd-Fe-B永磁合金的粉末冶金工艺提?
The phase diagram of Nd-Fe-B (B≤50at.%) Ternary system has been studied by means of X-ray diffraction, thermal analysis and magnetic measurement. The main results are as follows: 1. , To confirm the NdFe2 phase does not exist. The ternary room temperature cross section of Nd-Fe-B (B≤50at.%) Was determined. There are three compounds in this ternary system: Nd 2 Fe 14 B, Nd 8 Fe 27 B 24 and Nd 2 FeB 3. It is pointed out that in the non-annealed Nd-Fe-B ternary alloy, there is a possibility of supercooled liquid phase (amorphous). The practical Nd-Fe-B permanent magnet alloy consists of three phases, the main phase is Nd 2 Fe 14 B, the minor phase is Nd and Nd 8Fe 27 B 24. Determination of Fe_ (94) B_6-Nd_ (12) Fe_ (82) B_6-Nd_ (33.5) Fe_ (60.5) B_6 and Nd_2Fe_ (17) -Nd_2Fe_ (14) B_ Nd_8Fe_ (27) B_ section. It is pointed out that in the preparation of Nd-Fe-B ternary permanent magnet alloys, the maximum sintering temperature is not higher than 1100 ℃, and the temperature of the heat treatment is about 600 ℃. The structure of Nd 2 Fe 14 B, Nd 8 Fe 27 B 24 and the single phase region of Nd 2 Fe 14 B were studied. Nd 2 Fe 14 B is tetragonal, a = 8.800, c = 12.190, z = 4, the space group is P4_2 / mnm, the X-ray density is D_X = 7.60g / cm_3, the measured density is D_O = 7.50g / 3. Within the range of measurement accuracy, no single phase region of Nd 2 Fe 14 B was observed. The space group of Nd_8Fe_ (27) B_ (24) is tetragonal, a = 7.12, c = 27.40, z = 2, D_X = 7.01g / cm_3 and D_O = 7.00g / n. Based on the experiment, the thermal stability of Nd 2 Fe 14 B was discussed and the powder metallurgy process for preparing Nd-Fe-B permanent magnet alloy was proposed.