Electromagnetic wave absorption properties of FeCoNiCrAl 0.8 high entropy alloy powders and its amorphous structure prep
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We investigated FeCoNiCrAl0.8 high entropy alloy and amorphous alloy powders synthesized simply via high energy ball milling for 10 and 20 h. The electromagnetic wave absorption properties of FeCoNiCrAl0.8 high entropy alloy and amorphous alloy powders were investigated. The structure and morphology of FeCoNiCrAl0.8 were analyzed by scanning electron microscopy with energy-dispersive spectrometry and x-ray diffraction, which demonstrated that FeCoNiCrAl0.8 powders were in irregular shape and monodisperse with an average size of 5–15 lm. The minimum reflection loss of FeCoNiCrAl0.8 high entropy alloy powders was 41.8 dB at 11.9 GHz with a thickness of 2.3 mm and effective bandwidth (RL # 10 dB) was up to 4.7 GHz (8.7–13.4 GHz), while the minimum reflection loss of FeCoNiCrAl0.8 amorphous alloy powders was observed to be 35.5 dB at 14.6 GHz with a thickness of 1.7 mm and effective bandwidth varied from 12.7 to 16.3 GHz (3.6 GHz). Electromagnetic wave absorption properties of FeCoNiCrAl0.8 high entropy alloy powders is better than that of amorphous alloy powders, which demonstrated that phase structures of FeCoNiCrAl0.8 alloy powders affect electromagnetic wave absorption properties.
I. INTRODUCTION
In recent years, much attention has been focused on the research of high entropy alloys (HEAs) because of their potential properties such as high hardness, excellent ductility, and promising corrosion resistances, electrical and extraordinary mechanical properties.1–5 Above all, FeCoNiCrAl, as a traditional HEAs system, have been investigated widely. Besides the above-mentioned properties, the magnetic properties of FeCoNiCrAl HEAs have been one of the hot research topics.6–8 For instance, Chen investigated the magnetic property of Fe0.6CoNiCrAl HEA with saturation magnetization (Ms) of 50.70 emu/g and coercivity (Hc) of 31.3 Oe, respectively.9 Lu prepared the FeCoNiCrAl HEA and showed that its Ms was 59 emu/g and Hc was 36.6 Oe.10 It is well known that electromagnetic (EM) wave absorbers can effectively absorb EM waves by either dissipating EM wave loss or converting EM energy into thermal energy.11–16 Magnetic metallic powder materials, acting as one of EM wave absorption materials and combining both dielectric loss and magnetic loss, have shown a clear advantage in balancing the complex relative permittivity and permeability.17–21 FeCoNiCrAl HEAs with outstanding magnetic properties Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.257 2398
J. Mater. Res., Vol. 31, No. 16, Aug 29, 2016
http://journals.cambridge.org
Downloaded: 28 Aug 2016
can be used as EM wave absorbing materials. However, as far as we know, few researches have been reported about the electromagnetic wave absorption properties of FeCoNiCrAl HEAs powders. HEAs powders are often prepared by mechanical alloying with enough time or atomization method with gas or liquid.22–24 In particular, mechanical alloying, which is of utmost interest in the last decades, allows one to
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