Vol.2, No.1, 18-25 (2010) Natural Science
http://dx.doi.org/10.4236/ns.2010.21003
Copyright © 2010 SciRes. OPEN ACCESS
Hydriding and dehydriding kinetics of melt spun
nanocrystalline Mg20Ni10-xCux (x = 0-4) alloys
Yang-Huan Zhang1,2,*, Dong-Liang Zhao1, Bao-Wei Li2, Hui-Ping Ren1, Shi-Hai Guo1, Xin-Lin Wang1
1Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing, China
2School of Material, Inner Mongolia University of Science and Technology, Baotou, China; zyh59@yahoo.com.cn
Received 22 October 2009; revised 13 November 2009; accepted 17 November 2009.
ABSTRACT
The nanocrystalline Mg2Ni-type electrode alloys
with nominal compositions of Mg20Ni10-xCux (x =
0, 1, 2, 3, 4) were synthesized by melt-spinning
technique. The microstructures of the alloys
were characterized by XRD, SEM and HRTEM.
The hydrogen absorption and desorption kinet-
ics of the alloys were measured using an auto-
matically controlled Sieverts apparatus. The re-
sults show that all the as-spun alloys hold ty-
pical nanocrystalline structure. The substitution
of Cu for Ni does not change the major phase
Mg2Ni but it leads to the formation of the sec-
ondary phase Mg2Cu. The hydrogen absorption
capacity of the alloys first increases and then
decreases with rising Cu content, but the hy-
drogen desorption capacity of the alloys mono-
tonously grows with increasing Cu content. The
melt spinning significantly improves the hydro-
genation and dehydrogenation capacities and
kinetics of the alloys.
Keywords: Mg2Ni-Type Alloy; Substituting Ni with
Cu; Melt Spinning; Hydriding and Dehydriding
Kinetics
1. INTRODUCTION
Mg and Mg-based alloys has been considered as poten-
tial materials for solid state hydrogen storage in the form
of metallic hydrides such as MgH2 and Mg2NiH4. The
theoretical hydrogen storage capacities of MgH2 and
Mg2NiH4 are 7.6 wt.% and 3.6 wt.% [1,2] respectively,
which is quite adequate for commercial applications as a
hydrogen fuel source [3]. Unfortunately, the slow sorp-
tion/desorption kinetics and high dissociation tempera-
ture of these kinds of metal hydrides limit their practical
application. Therefore, finding ways of improving the
hydration kinetics of Mg-based alloys has been one of
the main challenges faced by researchers in this area.
Various attempts, involving mechanical alloying (MA)
[4], GPa hydrogen pressure method [5], melt spinning
[6], gravity casting [7], polyol reduction [8], hydriding
combustion synthesis [9], surface modification [10], al-
loying with other elements [11,12], adding catalysts [13]
etc, have been undertaken to improve the activation and
hydriding property.
Gennari et al. [14] reported that the nanocrystalline
Mg2Ni synthesized by combined milling-annealing pro-
cedure can readily hydrogen absorption during the first
cycle and show excellent absorption kinetics at 200.
Muthukumar et al. [15] confirmed that a maximum hy-
drogen capacity of 3.67 wt.% for the Mg2Ni alloy pre-
pared by mechanical alloying (MA) could be achieved
for an initial absorption temperature of 300 and sup-
ply pressure of 20 bar. Recham et al. [16] found that the
hydrogen absorption property of ball-milled MgH2 can
be enhanced by adding NbF5, and the milled MgH2+
NbF5 composite can desorbs 3 wt.% H2 at 150. Do-
brovolsky et al. [17] synthesized a MgH2 (50 wt.%) +
TiB2 (50 wt.%) composite by intensive mechanical mil-
ling and found that TiB2 addition decreases the dissocia-
tion temperature of the MgH2 hydride by about 50.
Indubitably, ball-milling is a very effective method for
the preparation of nanocrystalline and amorphous Mg
and Mg-based alloys. Particularly, it is suitable to solu-
bilize particular elements into MgH2 or Mg2NiH4 above
the thermodynamic equilibrium limit, which is helpful to
destabilize MgH2 or Mg2NiH4 [18]. However, the milled
Mg and Mg-based alloys show very poor hydrogen ab-
sorbing and desorbing stability due to the fact that the
metastable structures formed by ball milling tended to
vanish during multiple hydrogen absorbing and desorb-
ing cycles [19]. Alternatively, melt-spun technique can
overcome the above mentioned shortcoming and effec-
tive avoiding the significant degradation of hydrogen
absorbing and desorbing cycle properties of Mg and Mg-
based [20]. Additionally, the melt-spinning technique is
a very effective method to obtain a nanocrystalline struc-
ture and is very suitable for mass-production of nano-
crystalline Mg-based alloys. It was also clarified that
nanocrystalline alloys produced by melt-spinning could
Y. H. Zhang et al. / Natural Science 2 (2010) 18-25
Copyright © 2010 SciRes. OPEN ACCESS
19
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have excellent hydriding characteristics even at room
temperature, similar to the alloys produced by the MA
process. Spassov et al. [21] prepared Mg2(Ni, Y) hydro-
gen storage alloy with exact composition Mg63Ni30Y7 by
rapid solidification, and its maximum hydrogen absorp-
tion capacity (about 3.0 wt.%) and hydrogenation kinet-
ics of the as-spun Mg2(Ni, Y) alloy were found to ex-
ceed those of the polycrystalline Mg2Ni alloys prepared
by conventional technology and to be comparable to the
hydrogen absorption characteristics of ball-milled na-
nocrystalline Mg2Ni. It was determined that the addition
of third element stabilizes the nanostructure of Mg-Ni
based alloy, which could be very important for practical
H-storage materials.
Our previous work indicated that the substitution of
Co for Ni significantly improved the hydriding and de-
hydriding kinetics of the Mg2Ni-type alloys [22]. There-
fore, it is very desirable to investigate the influence of
substituting Ni with Cu on the hydriding and dehydrid-
ing characteristics of Mg2Ni-type alloys prepared by
melt-spinning. The objective of this work is to produce
the Mg-Ni-based ternary nanocrystalline alloys by melt
spinning and to examine their structures and hydriding
and dehydriding kinetics.
2. EXPERIMENTAL METHODS
The alloy ingots were prepared using a vacuum induc-
tion furnace in a helium atmosphere at a pressure of 0.04
MPa. Part of the as-cast alloys was re-melted and spun
by melt-spinning with a rotating copper roller. The spin-
ning rate was approximately expressed by the linear ve-
locity of the copper roller because it is too difficult to
measure a real spinning rate i.e. cooling rate of the sam-
ple during spinning. The spinning rates used in the ex-
periment were 15, 20, 25 and 30 m/s, respectively. The
nominal compositions of the experimental alloys were
Mg20Ni10-xCux (x = 0, 1, 2, 3, 4). For convenience, the
alloys were denoted with Cu content as Cu0, Cu1, Cu2,
Cu3 and Cu4, respectively.
The morphologies of the as-cast alloys were observed
by scanning electron microscope (SEM) (Philips Q-
UANTA 400). The phase structures of the as-cast and
spun alloys were determined by XRD diffractometer (D/
max/2400). The diffraction, with the experimental pa-
rameters of 160 mA, 40 kV and 10°/min respectively,
was performed with CuKα1 radiation filtered by graphite.
The thin film samples of the as-spun alloys were pre-
pared by ion etching for observing the morphology with
high resolution transmission electron microscope (H-
RTEM) (JEM-2100F, operated at 200 kV), and for de-
termining the crystalline state of the samples with elec-
tron diffraction (ED).
The hydrogen absorption and desorption kinetics of
the alloys were measured by an automatically controlled
Sieverts apparatus. The hydrogen absorption was con-
ducted at 1.5 MPa at 200 and the hydrogen desorp-
tion in a vacuum (1×10-4 MPa) at 200 too.
3. RESULTS AND DISCUSSIONS
3.1. Microstructure Characteristics
The SEM images of the as-cast alloy are illustrated in
Figure 1, displaying a typical dendrite structure. The
substitution of Cu for Ni does not change the morphol-
ogy of the alloys but it causes a significant refinement of
the grains. The result obtained by energy dispersive
spectrometry (EDS) indicates that the major phase of the
as-cast alloys is Mg2Ni phase (denoted as A). Some
small massive matters in the alloys containing Cu can
clearly be seen in Figure 1, which are determined by
EDS to be Mg2Cu phase (denoted as B).
Figure 2 presents the XRD profiles of the as-cast and
spun Mg20Ni10-xCux (x = 0, 1, 2, 3, 4) alloys, showing
that the substitution of Cu for Ni does not change the
phase structure. All the as-cast and spun alloys display a
single phase structure. This seems to be contrary with
the result of SEM observation. It is most probably asso-
ciated with the fact that Mg2Ni and Mg2Cu hold com-
pletely identical structure and nearly same lattice con-
stants. On the other hand, the amount of the Mg2Cu
phase is very little so that the XRD observation can not
detect its presence. Listed in Table 1 are the lattice pa-
rameters, cell volume and full width at half maximum
(FWHM) values of the main diffraction peaks of the
as-cast and spun (20 m/s) alloys which were calculated
by software of Jade 6.0. It can be derived from Table 1
that the substitution of Cu for Ni causes the FWHM
values of the main diffraction peaks of the as-cast and
spun alloys significantly increased, and it leads to the
lattice parameters and cell volume of the alloys cleverly
enlarged, which is attributed to the slightly larger atomic
radius of Cu than Ni. It can be seen from Table 1 that
melt spinning causes the FWHM values of the main dif-
fraction peaks of the alloys significantly increased which
is doubtless attributed to the refinement of the grains and
the stored stress in the grains produced by melt spinning.
Based on the FWHM values of the broad diffraction
peak (203) in Figure 2b, the crystallite size <Dhkl > (Ǻ)
of the as-spun alloy was calculated using Scherrer’s
equation. The grain sizes of the as-spun alloys are in a
range of 2-6 nm, consistent with results reported by
Friedlmeier et al. [23]. It is very important to notice that
<D> values were calculated on the same peak having
Miller indices (203) due to better possibility of mutual
comparison.
Figure 3 shows HRTEM micrographs and electron
diffraction patterns of the as-spun Cu1 and Cu3 alloys,
which reveal a nanocrystalline microstructure, with an
average crystal size of about 2-5 nm. This result agrees
very well with the XRD observation shown in Figure 2.
Y. H. Zhang et al. / Natural Science 2 (2010) 18-25
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20
From HRTEM observations there is some evidence that
the as-spun alloys are strongly disordered and nanos-
tructured, but they are free of amorphous phase. Spassov
et al. [21] reported that Mg-based alloys with nanocrys-
talline microstructures can be obtained by controlling the
cooling rates. The crystal defects in the as-spun alloy,
stacking faults (denoted as A), twin-grain boundaries
(denoted as B), dislocations (denoted as C) and sub-
grain boundaries (denoted as D), can clearly be seen in
Figure 4.
Figure 1. SEM images of the as-cast alloys together with EDS spectra of sections A and B in
Figure 1 (b): (a) Cu0 alloy, (b) Cu4 alloy.
Figure 2. XRD profiles of the as-cast and spun alloys: (a) As-cast, (b) As-spun (20 m/s).
a
20 μm
A
b
20 μm
B
A
Section A
0 2 4 6 8
Mg
N
i
N
i
Cu Cu
keV
Mg
Cu
N
i
Cu
Section B
02468 10
keV
20 30 40 50 60 70 80 90100
(403)
(204)
(220)
(118)
(215)
(206)
(203)
(113) (105)
(200)
(112)
(103)
(102)
(101) (003)
(100)
Cu0
2θ(de g re e )
Cu1
Cu2
Cu3
(b)
Cu4
△ -Mg2Ni
20 30 40 50 60 70 80 90100
(403)
(204)
(220)
(118)
(215)
(206)
(212)
(211)
(106) (203)
(113)(105)
(200)
(112)
(103)
(102)
(101) (003)
(100)
Cu0
2θ(deg r ee)
Cu1
Cu2
Cu3
(a) △ -Mg2Ni Cu4
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Table 1. The lattice parameters, cell volume and the FWHM values of the major diffraction peaks of the alloys.
Figure 3. HRTEM micrographs and ED of the as-spun alloys (30 m/s): (a) Cu1 alloy (b) Cu3 alloy.
Figure 4. Crystal defects in the as-spun (30 m/s) Cu3 alloy taken by HRTEM: (a) Stacking fault, (b) Twin grain bound-
ary, (c) Dislocations and sub-grain boundaries.
3.2. Hydriding and Dehydriding Characteristics
Figure 5 shows the hydrogen absorption capacity and
kinetics of the as-cast and spun Cu1 and Cu3 alloys. It
can be seen that all the hydriding kinetic curves of the
as-spun alloys show an initial fast hydrogen absorption
stage after which the hydrogen content is saturated at
longer hydrogenation time, indicating that the melt spin-
ning significantly improves the hydrogen absorption
property of the alloys. The hydrogen absorption capaci-
ties of the alloys increase with rising spinning rate.
When the spinning rate grows from 0 (As-cast is defined
as spinning rate of 0 m/s) to 30 m/s, the hydrogen ab-
sorption capacity of the Cu1 alloy in 10 min rises from
1.99 to 3.12 wt.%, and from 1.74 to 2.88 wt.% for the
Cu3 alloy.
The hydrogenation kinetics and storage capacity of all
the as-spun nanocrystalline Mg2Ni-type alloys studied
FWHM values Lattice parameters and cell volume
2θ(20.02°) 2θ(45.14°) a (Å) c (Å) V (Å3)
Alloys
As-cast 20m/s As-cast 20m/sAs-cast20 m/sAs-cast 20 m/s As-cast 25 m/s
Cu0 0.122 0.129 0.169 0.1735.20975.210113.244 13.258 311.29 311.67
Cu1 0.133 0.184 0.178 0.2185.21025.215413.252 13.262 311.54 312.39
Cu2 0.148 0.232 0.183 0.2235.21365.216213.283 13.307 312.67 313.55
Cu3 0.151 0.257 0.192 0.2325.21545.217113.297 13.313 313.22 313.80
Cu4 0.165 0.286 0.204 0.2525.21715.220313.302 13.317 313.54 314.28
50 nm
a
50 nm
5 nm
a
A
b
5 nm
5 nm
c
D
C
B
Y. H. Zhang et al. / Natural Science 2 (2010) 18-25
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22
Figure 5. Hydrogen absorption kinetic curves of the as-cast and spun alloys: (a) Cu1 alloy (b) Cu3 alloy.
are superior to those of conventional polycrystalline ma-
terials with similar composition. The enhanced hydro-
genation property by melt spinning is undoubtedly asso-
ciated with the refinement of the grains produced by
melt spinning [24]. By refining the microstructure, a lot
of new crystallites and grain boundaries are created
which can act as fast diffusion paths for hydrogen ab-
sorption. Based on the result reported by Orimo and Fu-
jii [25], the distribution of the maximum hydrogen con-
centrations in three nanometer-scale regions, i.e. grain
region and grain boundary region as well as amorphous
region, have been experimentally determined to be 0.3
wt.% H in the grain region of Mg2Ni, 4.0 wt.% H in the
grain boundary and 2.2 wt.% H in the amorphous region.
It revealed that the hydrides mainly exist in grain-
boundary region and the amorphous phase region. The
improved hydrogenation characteristics can be explained
with the enhanced hydrogen diffusivity in the nanocrys-
talline microstructure as the nanocrystalline leads to an
easier access of hydrogen to the nanograins, avoiding the
long-range diffusion of hydrogen through an already
formed hydride, which is often the slowest stage of ab-
sorption. It is known that the nanocrystalline micro-
structures can accommodate higher amounts of hydrogen
than polycrystalline ones. The crystalline material, when
melt spun, becomes at least partially disordered and its
structure changes to nanocrystalline. Consequently, high
densities of crystal defects such as dislocations, stacking
faults and grain boundaries are introduced. The large
number of interfaces and grain boundaries available in
the nanocrystalline materials provide easy pathways for
hydrogen diffusion and accelerates the hydrogen ab-
sorbing/desorbing process.
The hydrogen absorption kinetic curves of the as-spun
alloys are plotted in Figure 6. It can be seen that the
hydrogen absorption capacity of as-spun alloys first in-
creases and then decreases with the variation of Cu con-
tent. The Cu2 alloy shows a maximum hydrogen absorp-
tion capacity at 200. The kinetics of hydrogenation
was extremely fast so that the alloys absorbed more than
95% of their hydrogen capacities within the first 5 min.
The excellent hydriding kinetics is ascribed to the na-
nocrystalline structure because the high surface to vol-
ume ratios (high specific surface area) and the presence
of large number of grain boundaries in nanocrystalline
alloys enhance the kinetics of hydrogen absorption/ de-
sorption. The positive function of Cu substitution on the
hydrogen absorption capacity and kinetics of the alloy is
attributed to the increased cell volume and the grain re-
fined by Cu substitution. The increase of the cell volume
is very helpful to hydrogen absorption capacity, and the
grain boundary possesses the largest hydrogen absorp-
tion capability [25]. It was well known that the catalytic
action of Ni on hydriding is stronger than Cu. Therefore,
it is understandable that a superfluous amount of Cu
substitution (x>2) must lead to a decrease of the hydro-
gen absorption capacity of the alloys.
Figure 7 shows the hydrogen desorption capacity and
kinetics of the as-cast and spun Cu1 and Cu3 alloys, in-
dicating that the dehydriding capability of the alloys
obviously meliorates with rising spinning rate. When the
spinning rate grows from 0 to 30 m/s, the hydrogen de-
sorption capacity of the Cu1 alloy in 20 min increases
from 0.29 to 0.98 wt.%, and from 0.52 to 1.49 wt.% for
Cu3 alloy, respectively. The nanocrystalline Mg2Ni-
based alloys produced by melt spinning exhibit higher
H-absorption capacity and faster kinetics of hydriding/
dehydriding than crystalline Mg2Ni. A similar result was
reported by Spassov et al. [21]. The specific capacity
and hydriding/dehydriding kinetics of hydride materials
depend on their chemical composition and crystalline
structure [26]. The observed essential differences in the
hydriding/dehydriding kinetics of the melt-spun nano-
crystalline Mg2Ni type alloys studied most probably
have to be associated with the composition of the alloy
as well as with the differences in their microstructure
due to the different spinning rates. It was reported that
0 20406080100120
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
(a)
Hydrogen absorptiom (wt.%)
Time (min)
As-cast
15 m/s
20 m/s
25 m/s
30 m/s
0 20406080100120
0.0
0.5
1.0
1.5
2.0
2.5
3.0 (b)
Hydrogen absorption (wt.%)
Time (min)
As-cast
15 m/s
20 m/s
25 m/s
30 m/s
Y. H. Zhang et al. / Natural Science 2 (2010) 18-25
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the high surface to volume ratios, i.e. high specific sur-
face area, and the presence of large number of grain
boundaries in nanocrystalline alloys enhance the kinetics
of hydrogen absorption/desorption [21]. Zaluski et al.
[27] and Orimo et al. [28] confirmed that the hydriding/
dehydriding characteristics at low temperatures (lower
than 200) of nanocrystalline Mg2Ni alloys prepared by
mechanical alloying can be improved by reducing the
grain size (20-30 nm), due to hydrogen occupation in the
disordered interface phase.
The hydrogen desorption kinetic curves of the as-spun
alloys are plotted in Figure 8. An important feature of
the dehydrogenation process in the alloys is very slow
initial hydrogen desorption, followed by slack increase
in the amount of hydrogen desorbed. Figure 8 indicates
that the Cu substitution significantly improves the hy-
dogen desorption capacity and kinetics of the alloys.
When Cu content x increases from 0 to 4, the hydrogen
desorption capacity of the as-spun (20 m/s) alloy in 20
min rises from 0.62 to 1.43 wt.%, and from 0.89 to 1.69
wt.% for the as-spun (30 m/s) alloy. Several possibilities
can be considered as the reasons why the substitution of
Cu for Ni enhances the hydrogen desorption kinetics of
Mg2Ni-type alloys. Firstly, the partial substitution of
element Cu for Ni in Mg2Ni compound decreases the
stability of the hydride and makes the desorption reac-
tion easier [29]. Secondly, the presence of Mg2Cu phase
apparently has catalytic effects for the hydriding and
dehydriding reactions of Mg and Mg-based alloys [19].
Additionally, the addition of the third element Cu proba-
bly stabilizes the nanostructure of the alloy obtained by
melt spinning, which could be very important for practi-
cal H-storage materials on the base of Mg2Ni. In multi-
component Mg-based hydrogen storage alloys surface
segregation and formation of microcrack passages for H-
diffusion improve the kinetics of hydriding/dehydriding.
Figure 6. Hydrogen absorption kinetic curves of the as-spun alloys: (a) 20 m/s, (b) 30 m/s.
Figure 7. Hydrogen desorption kinetic curves of the as-cast and spun alloys: (a) Cu1 alloy (b) Cu3 alloy.
0 20406080100120
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
(b)
Hydrogen absorption (wt.%)
Time (min)
Cu0
Cu1
Cu2
Cu3
Cu4
020406080100120
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0.5
1.0
1.5
2.0
2.5
3.0
3.5
(a)
Hydrogen absorption (wt.%)
Time (min)
Cu0
Cu1
Cu2
Cu3
Cu4
020 40 60 80100120
0.0
0.2
0.4
0.6
0.8
1.0
1.2 (a)
Hydrogen desorption (wt.%)
Time (min)
As-cast 25 m/s
15 m/s 30 m/s
20 m/s
020 40 60 80100120
0.0
0.4
0.8
1.2
1.6
2.0 (b)
Hydrogen desorption (wt.%)
Time (min)
As-cast 25 m/s
15 m/s 30 m/s
20 m/s
Y. H. Zhang et al. / Natural Science 2 (2010) 18-25
Copyright © 2010 SciRes. OPEN ACCESS
24
Figure 8. Hydrogen desorption kinetic curves of the as-spun alloys: (a) 20 m/s, (b) 30 m/s.
4. CONCLUSIONS
1) All the as-spun Mg20Ni10-xCux (x = 0, 1, 2, 3, 4) alloys
hold nanocrystalline structures and are free of amor-
phous phase. The substitution of Cu for Ni does not
change the major phase of the alloy, but it leads to a sig-
nificant refinement of the grains and the formation of
secondary phase Mg2Cu in the as-cast alloys.
2) Melt spinning significantly improves the hydriding
and dehydriding properties of the alloys. Hydriding and
dehydriding capacities and rates of the alloy markedly
rise with increasing spinning rate, which is mainly at-
tributed to the formation of the nanocrystalline structure
caused by melt spinning.
3) With the substitution of Cu for Ni, the hydrogen
absorption capacity of the alloys first increases and then
decreases. But it clearly improves the hydrogen desorp-
tion capacity and dehydriding rate of the alloys, for
which the decreased stability of the hydride by Cu sub-
stitution is mainly responsible.
5. ACKNOWLEDGEMENTS
This work is supported by Hi-Tech Research and Development Pro-
gram of China (2007AA03Z227), National Natural Science Founda-
tions of China (50871050 and 50701011), Natural Science Foundation
of Inner Mongolia, China (200711020703) and Higher Education Sci-
ence Research Project of Inner Mongolia, China (NJzy08071).
REFERENCES
[1] Schlapbach, L. and Züttel, A. (2001) Hydrogen-storage
materials for mobile applications [J]. Nature, 414, 353-
358.
[2] Simičić, M.V., Zdujić, M., Dimitrijević, R., et al. (2006)
Hydrogen absorption and electrochemical properties of
Mg2Ni-type alloys synthesized by mechanical alloying
[J]. Journal of Power Sources, 158, 730-734.
[3] Schlapbach, L. (2002) Hydrogen as a fuel and its storage
for mobility and transport [J]. MRS Bulletin, 27, 675-676.
[4] Ebrahimi-Purkani, A. and Kashani-Bozorg, S.F. (2008)
Nanocrystalline Mg2Ni-based powders produced by
high-energy ball milling and subsequent annealing [J].
Journal of Alloys and Compounds, 456, 211-215.
[5] Kyoi, D., Sakai, T., Kitamura, N., et al. (2008) Synthesis
of FCC Mg-Ta hydrides using GPa hydrogen pressure
method and their hydrogen-desorption properties [J].
Journal of Alloys and Compounds, 463, 306-310.
[6] Palade, P., Sartori, S., Maddalena, A., et al. (2006) Hy-
drogen storage in Mg-Ni-Fe compounds prepared by
melt spinning and ball milling [J]. Journal of Alloys and
Compounds, 415, 170-176.
[7] Song, M.Y., Yim, C.D., Bae, J.S, et al. (2008) Prepara-
tion by gravity casting and hydrogen-storage properties
of Mg-23.5 wt.%Ni-(5, 10 and 15 wt.%)La [J]. Journal
of Alloys and Compounds, 463, 143-147.
[8] Hima Kumar, L., Viswanathan, B. and Srinivasa Murthy
S. (2008) Hydrogen absorption by Mg2Ni prepared by
polyol reduction [J]. Journal of Alloys and Compounds,
461, 72-76.
[9] Liu, X.F., Zhu, Y.F. and Li, L.Q. (2008) Structure and
hydrogenation properties of nanocrystalline Mg2Ni pre-
pared by hydriding combustion synthesis and mechanical
milling [J]. Journal of Alloys Compounds, 455, 197-202.
[10] Liu, F.J. and Suda, S. (1995) A method for improving the
long-term storability of hydriding alloys by air water ex-
posure [J]. Journal of Alloys Compounds, 231, 742-750.
[11] Czujko, T., Varin, R.A., Chiu, C., et al. (2006) Investiga-
tion of the hydrogen desorption properties of Mg+10
wt.% X (X = V, Y, Zr) submicrocrystalline composites
[J]. Journal of Alloys Compounds, 414, 240-247.
[12] Gasiorowski, A., Iwasieczko, W., Skoryna., et al. (2004)
Hydriding properties of nanocrystalline Mg2xMxNi al-
loys synthesized by mechanical alloying (M = Mn, Al)
[J]. Journal of Alloys Compounds, 364, 283-288.
[13] Sakintuna, B., Lamari-Darkrim, F. and Hirscher, M.
(2007) Metal hydride materials for solid hydrogen stor-
age: A review [J]. International Journal of Hydrogen
Energy, 32, 1121-1140.
[14] Gennari, F.C. and Esquivel, M.R. (2008) Structural char-
acterization and hydrogen sorption properties of
nanocrystalline Mg2Ni [J]. Journal of Alloys Compounds,
459, 425-432.
[15] Muthukumar, P., Prakash Maiya, M., Srinivasa Murthy,
020 40 60 80100120
0.0
0.4
0.8
1.2
1.6
2.0
(a)
Hydrogen desorption (wt.%)
Time (min)
Cu0 Cu3
Cu1 Cu4
Cu2
0 20406080100120
0.0
0.4
0.8
1.2
1.6
2.0 (b)
Hydrogen desorption (wt.%)
Time (min)
Cu0 Cu3
Cu1 Cu4
Cu2
Y. H. Zhang et al. / Natural Science 2 (2010) 18-25
Copyright © 2010 SciRes. OPEN ACCESS
25
25
S., et al. (2008) Tests on mechanically alloyed Mg2Ni for
hydrogen storage [J]. Journal of Alloys Compounds, 452,
456-461.
[16] Recham, N., Bhat, V.V., Kandavel, M., et al. (2008)
Reduction of hydrogen desorption temperature of ball-
illed MgH2 by NbF5 addition [J]. Journal of Alloys
Compounds, 464, 377-382.
[17] Dobrovolsky, V.D., Ershova, O.G., Solonin, Yu. M., et
al. (2008) Influence of TiB2 addition upon thermal sta-
bility and decomposition temperature of the MgH2 hy-
dride of a Mg-based mechanical alloy [J]. Journal of Al-
loys Compounds, 465, 177-182.
[18] Liang, G. (2004) Synthesis and hydrogen storage proper-
ties of Mg-based alloys [J]. Journal of Alloys Compounds,
370, 123-128.
[19] Song, M.Y., Kwon, S.N., Bae, J.S., et al. (2008) Hydro-
gen-storage properties of Mg-23.5Ni-(0 and 5)Cu pre-
pared by melt spinning and crystallization heat treatment
[J]. International Journal of Hydrogen Energy, 33,
1711-1718.
[20] Savyak, M., Hirnyj, S., Bauer, H.D., et al. (2004) Elec-
trochemical hydrogenation of Mg65Cu25Y10 metallic glass
[J]. Journal of Alloys Compounds, 364, 229-237.
[21] Spassov, T. and Köster, U. (1998) Thermal stability and
hydriding properties of nanocrystalline melt-spun
Mg63Ni30Y7 alloy [J]. Journal of Alloys Compounds, 279,
279-286.
[22] Zhang,Y.H., Li, B.W., Ren, H.P., et al. (2009) Hydriding
and dehydriding characteristics of nanocrystalline and
amorphous Mg20Ni10-xCox (x=0–4) alloys prepared by
melt-spinning [J]. International Journal of Hydrogen
Energy, 34, 2684-2691.
[23] Friedlmeier, G., Arakawa, M., Hiraia, T., et al. (1999)
Preparation and structural, thermal and hydriding char-
acteristics of melt-spun Mg-Ni alloys [J]. Journal of Al-
loys Compounds, 292, 107-117.
[24] Tanaka, K., Kanda, Y., Furuhashi, M., et al. (1999) Im-
provement of hydrogen storage properties of melt-spun
Mg-Ni-RE alloys by nanocrystallization [J]. Journal of
Alloys Compounds, 293-295, 521-525.
[25] Orimo, S. and Fujii, H. (2001) Materials science of
Mg-Ni-based new hydrides [J]. Applied Physics A, 72,
167-186.
[26] Mulas, G., Schiffini, L. and Cocco, G. (2004) Mechano-
chemical study of the hydriding properties of nanostruc-
tured Mg2Ni–Ni composites [J]. Journal of Materials
Research, 19, 3279-3289.
[27] Zaluski, L., Zaluska, A.J. and Ström-Olsen, O. (1997)
Nanocrystalline metal hydrides [J]. Journal of Alloys
Compounds, 253-254, 70-79.
[28] Orimo, S., Fujii, H. and Ikeda, K. (1997) Notable hy-
driding properties of a nanostructured composite material
of the Mg2Ni-H system synthesized by reactive me-
chanical grinding [J]. Acta Materialia, 45, 331-341.
[29] Woo, J.H. and Lee, K.S. (1999) Electrode characteristics
of nanostructured MgNi-type alloys prepared by me-
chanical alloying [J]. Journal of The Electrochemical So-
ciety, 146, 819-823.