高饱和磁感应强度软磁性钴基块体非晶合金的制备及其性能调控研究

The excellent soft magnetic properties of Co-based metallic glasses including low coercivity, high permeability, low core loss, and nearly zero magnetostriction coefficient, are of significant technical value. The practical applications of Co-based metallic glasses are limited by the low saturation magnetization (Bs) and weak glass-forming ability (GFA). Less experimental investigations have been carried out, and few theoretical guidelines are known, for the development of new types of Co-based metallic glasses with excellent soft-magnetic properties. This proposal is devoted to developing soft magnetic Co-based bulk metallic glasses (BMGs) with high Bs along with the relevant theoretical guidelines. Our experimental study is focusing on the alloying substitution effects of two groups of like-elements, (Fe, Ni or Mn) and (P, C or Si), and the minor alloying effects of rare earth and transition metal elements on the thermal stability, GFA, as well as the magnetic properties of binary Co-B alloys with high Co concentrations. Thereupon the experimental evidence is used to establish the relationship between the alloy composition, GFA, and magnetic properties. A local atomic structure model is put forth to understand the alloying effects on the microstructural evolution, and to elaborate the correlation between the composition, microstructure, GFA, and magnetic properties of the new type of Co-based BMGs, and then to clarify the microcosmic mechanism for tailoring the GFA and magnetic properties. Finally, Co-based BMGs with Bs > 1.1 T are to be obtained by composition optimization along with properties tailoring, and useful theoretical guidelines are to be proposed for the development of new Co-BMGs with excellent magnetic properties.

软磁性Co基非晶合金具有低矫顽力、高磁导率、低铁损、接近零的磁致伸缩系数等极其优异的软磁特性，有着重要的工业应用价值。但有关其新合金体系研发以及相关理论研究的工作很少。本项目针对Co基非晶合金饱和磁感应强度（Bs）不高及非晶形成能力（GFA）低的不足，以发展高Bs的优异软磁性Co基块体非晶合金为目标，系统研究（Fe，Ni，Mn）和（P，C，Si）两组相似元素、微量稀土和过渡金属元素的添加对高Co浓度Co-B二元合金的热稳定性、GFA及磁性能的影响规律，建立合金成分与GFA及磁性能的相关性。研究合金元素对其微观结构演变的影响规律，探讨成分—微观结构—GFA及磁性能间的关联，在原子层面理解合金元素的作用机理，阐明其对GFA和磁性能的微观调控机制。通过合金成分优化，综合调控合金的性能，制备出具有高Bs（> 1.1 T）Co基块体非晶合金，为发展新型优异软磁性能的Co基非晶合金提供实验和理论依据。

Co基非晶合金具有优异的软磁特性，但其饱和磁感应强度（Bs）不高及非晶形成能力（GFA）较低，限制了其应用范围。本项目以发展高Bs的软磁性Co基块体非晶合金为目标，研究了相似元素P，C，Si，Fe、微量稀土（RE）和前过渡金属（ETM）元素添加对Co-B合金热稳定性、GFA及磁性能的影响规律。研究合金元素对其微观结构演变的影响，探讨成分—微观结构—GFA及磁性能间的关联。通过成分优化，综合调控合金的性能，制备出高Bs的Co基块体非晶合金。.发现添加少量P可使Co-B-Si非晶合金出现玻璃化转变现象；以Fe置换Co-B-Si-P和Co-B-C-P合金中的Co，可显著增大其GFA，首次制备出了不含ETM和RE且Bs大于1.2 T的高强度Co基Co-Fe-B-Si-P和Co-Fe-B-C-P系块体非晶合金。该系合金的GFA与其过冷度的大小有较好的对应关系；从非晶合金结构均匀性以及磁致伸缩系数与磁各向异性的相关性的角度，说明了Fe量影响合金矫顽力（Hc）的机制。.在Co-B非晶合金添加少量Y，出现明显玻璃化转变现象，且Y量3.5 at.%合金具有最大的过冷液体温度区间（ΔTx）、GFA及最低Hc。第一原理分子动力学（AIMD）计算结果表明：添加3.5 at.%Y可提高合金原子间的相互作用，增强局域原子结构稳定性，降低过冷液态的扩散能力，从而提高合金的过冷液体稳定性和GFA；且Y3.5 at.%合金具有较小磁各向异性能和平均团簇尺寸是其低Hc主要原因。以Fe置换Co-RE-B非晶合金中的Co可明显增大其过冷液体稳定性和GFA，研发出了ΔTx和Bs分别大于60 K和1.1 T新型Co基(Co, Fe)-RE-B系块体非晶合金。. 在Co-Y-B和Co-Fe-Y-B非晶合金中添加少量Nb可显著增大其ΔTx和GFA，并提高软磁性。这是因为添加Nb提高了合金的畸变二十面体结构含量和B-B/Co-Y/B-Y原子间的相互作用，并起到连接Voronoi多面体的作用，增强了局域原子结构的稳定性的结果。.首次以快淬法制备出了具有高热稳定性、硬度的非金属B基B-Co-RE非晶合金。AIMD计算结果表明：以Co和RE为中心的较大团簇起到连接以B为中心的三棱柱型小团簇的作用，B-B和Co-B共价键形成的棱柱形团簇的致密堆积，均有利于增强合金局域原子结构稳定性，从而提高了其热稳定性和硬度。

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