Electromagnetic wave-absorbing behavior of soft-magnetic medium entropy alloys with BCC/L21 coherent microstructure. (October 2022)

• Record Type: Journal Article
• Authors: Ji, Zhiyao; Wang, Qing; Wang, Zhenhua; Duan, Yuping; Dong, Chuang; Liaw, Peter K.
• Is Part Of: Materials & design. Volume 222(2022)
• Publication Date: 2022-10
• Subjects: Medium-entropy alloys -- Coherent precipitation -- Soft-magnetic property -- Electromagnetic property; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2022.111054
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: The prominent soft magnetic properties are ascribed to their special coherent microstructure. A short-time ball-milling does not change the coherent BCC/ L21 structure of MEA powders. The prominent soft magnetic and high resistivity, which contributes to the excellent electromagnetic wave-absorbing properties. Al1.5 Co3.5 Fe3.5 flake powders possess the maximum effective bandwidth of 7.01 GHz with a sample thickness of 1.7 mm. Abstract: Magnetic alloy powders show a great superiority in the balance of permittivity and permeability for electromagnetic (EM) wave-absorption. However, it is necessary to enhance their effective absorption bandwidth ( Δf ) and impedance matching due to their insufficient soft-magnetic properties and low resistivity, which would be solved by high/medium-entropy alloys (HEAs/MEAs). In this report, we designed Al1.5 Co3.5 Fe3.5 and Al1.5 Co3 Fe3 Cr MEAs with prominent soft-magnetic property and high resistivity. It is contributed to the special coherent microstructure with ultrafine magnetic body-centered-cubic nanoprecipitates uniformly-distributed into the L21 matrix, which could not be changed by ball-milling. Thus, alloy powders possess excellent EM properties, as evidenced by the minimum reflection loss of −42.2 dB at 14.52 GHz and the largest Δf = 7.01 GHz in 5 h-milled Al1.5 Co3.5 Fe3.5, better than existing alloy powders. The wave-absorbing behavior of MEA powders was discussed from both permittivity and permeability. The current findings offer a useful design strategy for developing high-performance absorbers.