International Journal of Minerals, Metallurgy and Materials
Volume 21, Number 1, January 2014, Page 52
DOI: 10.1007/s12613-014-0864-2
Corresponding author: Jie Zhu E-mail: jiezhu@ustb.edu.cn
© University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg 2014
Influence of Al on the magnetostriction of Fe-Ga polycrystal alloys under
compressive stress
Long-long Liao, Mei-ling Fang, Jie Zhu, Ji-heng Li, and Jian Wang
State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
(Received: 24 June 2013; revised: 4 August 2013; accepted: 10 August 2013)
Abstract: Fe
80
Ga
20−x
Al
x
(x = 0, 6, 9, 14) ingots were prepared from high purity elements using a vacuum induction system. X-ray diffraction
patterns show that the alloys are A2 disordered structures. The influence of the partial substitution of Ga in Fe-Ga alloys with Al on their
magnetostrictive properties was investigated, and the effects of different heat treatment conditions on the magnetostriction and microstructure
of the alloy rods were also examined. The saturation magnetostriction value of Fe
80
Ga
20
can reach to 240 × 10
−6
under a compressive stress
of 20 MPa. The Fe
80
Ga
11
Al
9
alloy has many good properties, such as low hysteresis, high linearity of the magnetostriction curve, and low
saturated magnetic field, which make it a potential candidate for magnetostrictive actuator and transducer applications. It is found that sub-
grains have little influence on the magnetostriction of Fe-Ga alloys.
Keywords: iron-gallium alloys; polycrystals; aluminum; magnetostriction; compressive stress
1. Introduction
Fe-Ga alloys have attracted a lot of attention due to their
good mechanical properties and appreciable magnetostric-
tion in low saturation magnetic fields. They are widely used
in magnetostrictive actuators and sensors [1-4]. It has been
commonly believed that the increase in magnetostriction for
Fe-Ga alloys is because of the preferential (110) Ga-Ga
pairing in the disordered body centered cubic (bcc) structure.
Recently, it has been found that λ
100
exhibits two peaks near
19at% of 265 × 10
−6
and 27at% of 235 × 10
−6
[3]. The
magnetostriction value for directional solidified polycrystal-
line Fe
72.5
Ga
27.5
is up to 271 × 10
−6
in a low magnetic field [2].
Since the invention of Fe-Ga alloys, substantial research
has been carried out on different aspects of Fe-Ga and
Fe-Ga-Al alloys [5-10]. It was reported by Mungsantisuk
et al. [11] that the substitution of Ga with Al did not de-
crease the magnetostriction substantially in certain composi-
tion ranges. The same idea was expressed in the damping
properties of Fe-Ga-Al alloys [12]. The magnetostriction of
single crystal Fe
86.9
Ga
8.7
Al
4.4
as high as 160 × 10
−6
could be
obtained under a compressive stress of 25 MPa [4].
Fe-Ga-Al alloys were investigated for two main reasons: (1)
Al substitution can reduce the cost since the price of Ga
continues to increase; and (2) Al addition may help in the
development of Fe-Ga alloy rolled sheets.
In this paper, the magnetostrictive properties of Fe-Ga
and Fe-Ga-Al alloys under compressive stress were reported.
The influence of the partial substitution of Ga with Al on the
magnetostrictive properties of Fe-Ga alloys was investigated.
Furthermore, the effect of different heat treatment condi-
tions on the magnetostrictive properties of Fe
80
Ga
20−x
Al
x
(x =
0, 6, 9, 14) alloys was studied.
2. Experimental procedure
Ingots with nominal composition Fe
80
Ga
20−x
Al
x
(x = 0, 6,
9, 14) were prepared from iron (99.95% in purity), gallium
(99.95%), and aluminum (99.95%) under an argon atmos-
phere in a vacuum induction furnace. The as-cast ingots
were approximately 10 mm in diameter and were placed in
quartz tubes. Then, the ingots were directionally solidified
by using a directional solidification furnace. After confirm-
ing the completion of the melting process, the rods were al-
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