Enhanced Electromagnetic Interference Shielding of Mg-Zn-Zr Alloy by Ce Addition

doi:10.1007/s40195-015-0224-x

Abstract

Abstract:

The effects of Ce addition on microstructure and electromagnetic interference (EMI) shielding response of Mg-6Zn-0.5Zr (ZK60) alloy have been investigated. Ce addition resulted in grain refinement and higher density of Mg-Zn-Ce and MgZn₂ intermetallic particles in the alloy. In particular, this was substantially remarkable as the addition of Ce was up to 1.0 wt%. It is interesting to note that as-extruded ZK60 alloy with 1.0 wt% Ce addition exhibited an EMI shielding effectiveness (SE) exceeding 70 dB at the frequency range of 30-1,500 MHz, which was significantly higher than that of ZK60 alloy without Ce addition and reached the requirement of high protection. The superior SE was probably related to the increased reflection and multiple reflection of electromagnetic radiation induced by Ce addition. Direct artificial aging at 150 °C for 25 or 50 h led to a further increase of 7-10 dB in the SE of the alloy with 1.0 wt% Ce addition. The advantages of excellent shielding capacity and favorable mechanical strength make the Mg-Zn-Zr-Ce alloy an attractive shielding candidate material for a variety of technological applications.

Key words: Magnesium alloys, Ce Shielding effectiveness, Electromagnetic interference, Intermetallic particles

Xian-Hua Chen, Li-Zi Liu, Juan Liu, Fu-Sheng Pan. Enhanced Electromagnetic Interference Shielding of Mg-Zn-Zr Alloy by Ce Addition[J]. Acta Metallurgica Sinica (English Letters), 2015, 28(4): 492-498.

Figures/Tables 10

Table 1 Chemical compositions, average grain size (d), volume fraction of intermetallic particles (V f) and relative conductivity (σ r) for ZK60-xCe alloys

Alloy	Composition (wt%)			d (μm)	V _f (%)	σ _r (%)
Alloy	Zn	Zr	Ce	d (μm)	V _f (%)	σ _r (%)
ZK60	5.8	0.52	0	6.1	3.6	28.4
ZK60-0.5Ce	5.6	0.49	0.45	4.6	5.7	28.8
ZK60-1.0Ce	5.8	0.51	1.16	2.9	8.2	29.4

Fig. 1 XRD patterns of as-extruded ZK60-xCe alloys: a ZK60; b ZK60-0.5Ce; c ZK60-1.0Ce

Fig. 2 Typical optical micrographs of as-extruded ZK60-xCe alloys: a ZK60; b ZK60-0.5Ce; c ZK60-1.0Ce

Fig. 3 SEM images showing intermetallic particles in as-extruded ZK60 a, ZK60-0.5Ce b, ZK60-1.0 Ce c alloys, and the EDS result of point A d

Fig. 4 Typical TEM bright-field image as-extruded ZK60-1.0Ce alloy a and the magnified image of the region which is indicated by the frame b

Fig. 5 TEM bright-field micrographs showing Mg-Zn-Ce particles in as-extruded ZK60-1.0Ce alloy a, EDS results of particle A as indicated in a b, and SAED pattern obtained from particle A c

Fig. 6 Tensile engineering stress-strain curves of as-extruded ZK60-xCe alloys at room temperature

Fig. 7 Variation of EMI SE with testing frequency for as-extruded ZK60-xCe alloys

Fig. 8 Variation of EMI SE with testing frequency for ZK60-1.0Ce alloy in the extruded and aged states

Table 2 Comparison of EMI SE results between the ZK60-1.0Ce alloy and other shielding candidate materials

Material	Thickness (mm)	SE (dB)		References
Material	Thickness (mm)	f = 200 MHz	f = 1,200 MHz	References
Extruded ZK60 alloy	2	67	57	This work
Extruded ZK60-1.0Ce alloy	2	80	71	This work
Aged ZK60-1.0Ce alloy (150 °C/25 h)	2	86	81	This work
Cast pure Mg	2	63	53	[10]
Cast AZ31 alloy	2	68	60	[10]
2,024 Al alloy	2	37	35	[5]
Fly ash/2,024 Al alloy composite	2	53	31	[5]
1J50 magnetic alloy	2	80	68	[20]
Ni fibers/polyethersulfone	2.8	-	58	[1]
Steel fibers/polyethersulfone	2.8	-	42	[1]
Al flakes/polyethersulfone	2.8	-	26	[1]

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