Nb对非晶态Fe-Co-Nd-B合金的晶化动力学的影响

在Fe-Co-Nd-B非晶合金中添加4%的Nb(原子分数)可延迟其晶化过程, 提高晶化温度, 并使其热稳定性显著提高. Nb抑制Fe₃B晶化相的形核, 但促进Fe₂₃B₆相的形核及长大. Nb可使晶化相的平均晶粒尺寸从30-60 nm减至14-20 nm. Nb使由初始晶化温度计算的晶化激活能明显降低. Fe-Co-Nd-B合金中, α-Fe(Co), Fe₃B和Nd₂(Fe, Co)₁₄B晶化相的形核过程要难于长大过程, 而加Nb后α-Fe(Co), Fe₂₃B₆和Nd₂(Fe, Co)₁₄B晶化相的长大过程要难于形核过程, 但Nb基本未改变晶化相的形核及长大机制. 非晶合金的晶化主要是一维界面控制的形核以及形核率随时间减小的三维长大过程.

EFFECT OF Nb ON CRYSTALLIZATION KINETICS OF Fe-Co-Nd-B AMORPHOUS ALLOYS

The addition of 4% niobium in Fe-Co-Nb--B amorphous alloy may retard the crystallization process, raise the crystallized temperature and enhance the thermal stability. The nucleation of Fe₃B crystallized phase is checked while the nucleation and growth of Fe₂₃B₆ phase is promoted. The average grain sizes can be reduced from 30-60 nm to about 14-20 nm. The crystallization activation energy calculated by the onset crystallization temperatures decreases obviously. The nucleation process of α-Fe(Co), Fe₃B and Nd₂(Fe, Co)₁₄B phases is more difficult than the growth process, while the growth process of α-Fe(Co), Fe₂₃B₆ and Nd₂(Fe, Co)₁₄B phases is more difficult than the nucleation process caused by the addition of niobium. However, the mechanism of the nucleation and growth of the crystallized phases is almost unchanged. The crystallization process is mainly dominated by one-dimensional nucleation and three--dimensional growth with decreasing nucleation rate.