Finemet型納米晶軟磁合金的雙團(tuán)簇特征與成分優(yōu)化

Finemet型納米晶軟磁合金的雙團(tuán)簇特征與成分優(yōu)化Dual-Cluster Characteristic and Composition Optimization of Finemet Soft Magnetic Nanocrystalline Alloys

基于Finemet合金的成分及其非晶前驅(qū)體的晶化特征，提出了Finemet型合金的“雙團(tuán)簇”結(jié)構(gòu)模型和團(tuán)簇式成分，即Finemet合金的非晶前驅(qū)體可看作由2類(lèi)團(tuán)簇結(jié)構(gòu)構(gòu)成：一種為基于α-Fe(Si)有序固溶體（例如Fe3Si相）的[Si-Fe14](Cu1/13Si12/13)3弱穩(wěn)定團(tuán)簇結(jié)構(gòu)；另一種為對(duì)應(yīng)于Fe-B-Si-Nb系塊體非晶合金的[(Si,B)-B2(Fe,Nb)8]Fe強(qiáng)穩(wěn)定團(tuán)簇結(jié)構(gòu)。將2種團(tuán)簇成分式按等比例混合，設(shè)計(jì)并制備了多個(gè)新成分合金。熱分析和磁性測(cè)量結(jié)果表明，所有成分的非晶樣品均顯示多峰晶化特征，其中，[(Si0.8B0.2)-B2Fe7.2Nb0.8]Fe+[Si-Fe14](Cu1/13Si12/13)3（即Fe74B7.33Si15.23Nb2.67Cu0.77）非晶兩晶化峰的峰間距（ΔTp=Tp2-Tp1）最大，約為192 K。該非晶樣品在813 K等溫退火60 min后獲得典型的納米晶/非晶復(fù)相結(jié)構(gòu)，其飽和磁化強(qiáng)度Bs約為1.26 T、矯頑力Hc約為0.5 A/m、1 KHz下的有效磁導(dǎo)率μe約為8.5×105。新成分納米晶合金的綜合軟磁性能均優(yōu)于典型成分為Fe73.5Si13.5B9Cu1Nb3的已有Finemet納米晶合金。

The development of nanocrystalline Fe-Si-B-Nb-Cu alloys, commercially known as Finemet, has established a new approach to obtain soft-magnetic materials with high magnetic flux density. The material consists of α-Fe(Si) nanocrystals embedded in an amorphous matrix, which is made by means of partial crystallization. The composition and local structure of the precursor amorphous alloys are crucial for the formation of the unique nanocrystalline structure. The present study is devoted to understanding the composition characteristics and developing new compositions of Finemet alloys. Using the “cluster-plus-glue-atom” model and noticing the crystallization characteristic of Finemet alloy, a “dual-cluster” amorphous structure model is proposed. In this model, the precursor amorphous structure of Finemet alloy is considered to contain a mixture of the [(Si,B)-B2(Fe,Nb)8]Fe cluster derived from the Fe-B-Si-Nb bulk glassy alloys, and the [Si-Fe14](Cu1/13Si12/13)3 cluster from Fe3Si phase. A series of new Finemet nanocrystalline alloy compositions are designed by mixing [(Si,B)-B2(Fe,Nb)8]Fe and [Si-Fe14](Cu1/13Si12/13)3 cluster formulas with a ratio of 1:1. Thermal analysis results show that [(Si0.8B0.2)-B2Fe7.2Nb0.8]Fe+[Si-Fe14](Cu1/13Si12/13)3 (alloy composition: Fe74B7.33Si15.23Nb2.67Cu0.77) amorphous alloy exhibits a maximal temperature interval of ~192 K between the first and second crystallization peaks. Magnetic measurement results show that the Fe74B7.33Si15.23Nb2.67Cu0.77 nanocrystalline alloy exhibits optimal soft magnetic properties with a saturation magnetization of Bs ~ 1.26 T, a coercive force of Hc ~ 0.5A/m and an effective permeability of μe ~ 8.5×105 at 1 kHz after isothermal annealing at 813 K for 60 min. The soft magnetic properties of the new composition nanocrystalline alloys are better than that of the typical Finemet nanocrystalline alloy (Fe73.5Si13.5B9Cu1Nb3).

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