Hawelek Lukasz, Zackiewicz Przemyslaw, Wojcik Anna, Hudecki Jacek, Warski Tymon
Lukasiewicz Research Network-Institute of Non-Ferrous Metals, 5 Sowinskiego St., 44-100 Gliwice, Poland.
Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Krakow, Poland.
Materials (Basel). 2023 Sep 19;16(18):6288. doi: 10.3390/ma16186288.
The importance of amorphous and nanocrystalline Fe-based soft magnetic materials is increasing annually. Thus, characterisation of the chemical compositions, alloying additives, and crystal structures is significant for obtaining the appropriate functional properties. The purpose of this work is to present comparative studies on the influence of Nb (1, 2, 3 at.%) and Mo (1, 2, 3 at.%) in Fe substitution on the thermal stability, crystal structure, and magnetic properties of a rapidly quenched FeCoCuB alloy. Additional heat treatments in a vacuum (260-640 °C) were performed for all samples based on the crystallisation kinetics. Substantial improvement in thermal stability was achieved with increasing Nb substitution, while this effect was less noticeable for Mo-containing alloys. The heat treatment optimisation process showed that the least lossy states (with a minimum value of coercivity below 10 A/m and high saturation induction up to 1.7 T) were the intermediate state of the relaxed amorphous state and the nanocomposite state of nanocrystals immersed in the amorphous matrix obtained by annealing in the temperature range of 340-360 °C for 20 min. Only for the alloy with the highest thermal stability (Nb = 3%), the α-Fe(Co) nanograin grows, without the co-participation of the hard magnetic FeB, in a relatively wide range of annealing temperatures up to 460 °C, where the second local minimum in coercivity and core power losses exists. For the remaining annealed alloys, due to lower thermal stability than the Nb = 3% alloy, the FeB phase starts to crystallise at lower annealing temperatures, making an essential contribution to magneto-crystalline anisotropy, thus the substantial increase in coercivity and induction saturation. The air-annealing process tested on the studied alloys for optimal annealing conditions has potential use for this type of material. Additionally, optimally annealed Mo-containing alloys are less lossy materials than Nb-containing alloys in a frequency range up to 400 kHz and magnetic induction up to 0.8 T.
非晶态和纳米晶态铁基软磁材料的重要性正逐年增加。因此，对化学成分、合金添加剂和晶体结构进行表征对于获得合适的功能特性具有重要意义。本工作的目的是对Nb（1、2、3原子百分比）和Mo（1、2、3原子百分比）在Fe替代中对快速淬火FeCoCuB合金的热稳定性、晶体结构和磁性能的影响进行对比研究。基于结晶动力学，对所有样品在真空中（260 - 640°C）进行了额外的热处理。随着Nb替代量的增加，热稳定性有显著提高，而对于含Mo合金，这种效果不太明显。热处理优化过程表明，损耗最小的状态（矫顽力最小值低于10 A/m且饱和感应高达1.7 T）是通过在340 - 360°C温度范围内退火20分钟获得的弛豫非晶态和纳米晶体浸没在非晶基体中的纳米复合状态的中间状态。仅对于热稳定性最高的合金（Nb = 3%），α-Fe(Co)纳米晶粒在高达460°C的相对较宽退火温度范围内生长，且没有硬磁相FeB的共同参与，在此温度范围内存在矫顽力和磁芯功率损耗的第二个局部最小值。对于其余退火合金，由于热稳定性低于Nb = 3%的合金，FeB相在较低的退火温度下开始结晶，对磁晶各向异性有重要贡献，从而导致矫顽力和感应饱和度大幅增加。在研究合金上测试的空气退火过程为这种类型的材料提供了优化退火条件的潜在用途。此外，在高达400 kHz的频率范围和高达0.8 T的磁感应强度下，最佳退火的含Mo合金比含Nb合金的损耗更小。
