Journal of Alloys and Compounds 509S (2011) S197–S201
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Journal of Alloys and Compounds
journal homepage: www.elsevier.com/locate/jallcom
The characterization of structure, thermal stability and magnetic properties of
Fe–Co–B–Si–Nb bulk amorphous and nanocrystalline alloys
S. Lesz
a
, R. Babilas
a
, M. Nabialek
b,∗
, M. Szota
b
, M. Do ´ spial
b
, R. Nowosielski
a
a
Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Gliwice, Poland
b
Czestochowa University of Technology, Cz˛ estochowa, Poland
article info
Article history:
Received 5 August 2010
Received in revised form
14 December 2010
Accepted 17 December 2010
Available online 31 December 2010
Keywords:
Amorphous materials
Ferromagnetic materials
Magnetic hysteresis
X-ray measurements
abstract
Recently bulk amorphous alloys have attracted great attention due to their excellent magnetic proper-
ties. The glass-forming ability of bulk amorphous alloys depends on the temperature difference (T
x
)
between glass transition temperature (T
g
) and crystallization temperature (T
x
). The increase of T
x
causes a decrease of the critical cooling rate (V
c
) and growth of the maximum casting thickness of
bulk amorphous alloys. The aim of the present paper is to characterize the structure, the thermal
stability and magnetic properties of Fe
36
Co
36
B
19
Si
5
Nb
4
bulk amorphous alloys using XRD, Mössbauer
spectroscopy, DSC and VSM methods. Additionally the magnetic permeability
i
(at force H ≈ 0.5 A/m
and frequency f ≈ 1 kHz) and the intensity of disaccommodation of magnetic permeability /(t
1
)
( = (t
1
= 30 s) - (t
2
= 1800 s)), have been measured, where is the initial magnetic permeability
measured at time t after demagnetisation, the Curie temperature T
C
and coercive force H
c
of rods are also
determined with the use of a magnetic balance and coercivemeter, respectively.
Fe–Co–B–Si–Nb bulk amorphous alloys were produced by pressure die casting with the maximum
diameters of 1 mm, 2 mm and 3 mm.
The glass transition temperature (T
g
) of studied amorphous alloys increases from 807 K for a rod with a
diameter of 1 mm to 811 K concerning a sample with a diameter of 3 mm. The crystallization temperature
(T
x
) has the value of 838 K and 839 K for rods with the diameters of 1 mm and 3 mm, respectively. The
supercooled liquid region (T
x
= T
x
- T
g
) has the value of about 30 K. These values are presumed to be
the origin for the achievement of a good glass-forming ability of the Fe–Co–B–Si–Nb bulk amorphous
alloy. The investigated amorphous alloys in the form of rods have good soft magnetic properties (e.g.
M
s
= 1.18–1.24 T). The changes of crystallization temperatures and magnetic properties as a function of
the diameter of the rods (time of solidification) have been stated.
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
The first Fe-based bulk metallic glasses (BMGs) were prepared
in 1995 [1], since then, iron-based bulk metallic glasses have been
studied as a novel class of engineering materials, which have a good
glass forming ability and soft magnetic properties [1–6]. For exam-
ple, in 2004, Inoue et al. synthesized [(Fe
x
Co
1-x
)
0.75
B
0.2
Si
0.05
]
96
Nb
4
(x = 0.1 and -0.5 at.%). BMGs exhibit good soft magnetic properties,
as well as superhigh fracture strength of 3000–4000 MPa and duc-
tile strain of 0.002 [4]. Researching a Fe-based BMGs with high GFA
and excellent magnetic and mechanical properties, the effect of the
replacement of Fe by Co and alloying addition has been investi-
gated.
∗
Corresponding author at: Czestochowa University of Technology, Institute of
Physics, Armii Krajowej Av. 19, 42 200 Cz ˛ estochowa,
´
Slaskie, Poland.
Fax: +48 34 3250795.
E-mail address: nmarcell@wp.pl (M. Nabialek).
Newly developed Fe- and Co-based bulk metallic glasses are
attractive compared with conventional crystalline alloys and are
very useful in a wide range of engineering applications and their
application fields have a tendency to be extended widely. They are
suitable materials for many electrical devices such as electronic
measuring and surveillance systems, magnetic wires, sensors,
band-pass filters, magnetic shielding, precision mold material, pre-
cision imprint material, and cutting tool material [2,7,8].
In the present paper structure, the thermal stability and mag-
netic properties of Fe–Co–B–Si–Nb bulk amorphous alloys have
been characterized.
2. Experimental
Investigations were carried out on amorphous and partially crystallized rods
with the compositions of Fe36Co36B19Si5Nb4. Fe-based master alloy ingots with the
above compositions were prepared by induction melting of mixtures of pure Fe,
Co and Nb metals and pure B and Si crystals in an argon atmosphere. The alloy
compositions represent nominal atomic percentages.
0925-8388/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jallcom.2010.12.146