Materials Transactions, Vol. 43, No. 11 (2002) pp. 2662 to 2669
Special Issue on Protium New Function in Materials
c
2002
The Japan Institute of Metals
Hydrogen Internal Friction Peak in Amorphous Zr–Cu–Al–Si Alloys
Hiroshi Mizubayashi, Yasushi Ishikawa ∗ and Hisanori Tanimoto
Institute of Materials Science, University of Tsukuba, Tsukuba 305-8573, Japan
The hydrogen internal friction peak (HIFP) in amorphous (a-) Zr60 Cu40−y Al y (y = 0, 10), a-Zr50 Cu50 , a-Zr40 Cu60 and aZr40 Cu50−x Al10 Six (x = 0, 1, 3) are studied to pursue a high-strength and high-damping performance as well as the underlying process
for the HIFP in a-alloys. The tensile strength, σf , of a-Zr60 Cu30 Al10 , a-Zr40 Cu50 Al10 and a-Zr40 Cu49 Al10 Si1 increases from about 1.5 GPa to
2 GPa with increasing hydrogen concentration, C H , to 20 at%. One part of a-Zr60 Cu30 Al10 , a-Zr40 Cu50 Al10 and a-Zr40 Cu49 Al10 Si1 specimens
show a very high HIFP beyond 3 × 10−2 in the as hydrogen charged state, where the hydrogen induced structural relaxation (HISR) proceeds
−2 at
above room temperature. A maximum value of the HIFP, Q −1
p , after the HISR shows a moderate increase with increasing C H , about 1×10
data
indicates
that
a-Zr
Cu
Al
(H),
a-Zr
Cu
Al
(H)
and
a-Zr
Cu
Al
Si
(H)
after
the
C H of 10 at%. The combination of σf and Q −1
60
40 10
40
50 10
40
49 10 1
p
HISR are potential materials with a high-strength and high-damping performance. The peak temperature of the HIFP, Tp , at 10 at%H is 309 K,
270 K and 220 K with the measurement frequency of about 200 Hz for a-Zr40 Cu49 Al10 Si1 , a-Zr40 Cu50 Al10 and a-Zr60 Cu30 Al10 , respectively.
It is noted that Tp found for a-Zr40 Cu49 Al10 Si1 shows a breakthrough for an elevation of Tp of the HIFP in a-alloys, and that a composite
material composed of these a-alloys can serve a high-damping performance in a wide temperature range or a wide frequency range. For the
underlying process of the HIFP, the Q −1
p vs. C H data shows a camel’s humps like change for a-Zr50 Cu50 and a-Zr40 Cu60 , suggesting that only
one part of hydrogen atoms can contribute to the HIFP. In contrast, Q −1
p shows a monotonous increase with increasing C H for C H below
20 at% for a-Zr60 Cu40−y Al y (y = 0, 10) and a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3), suggesting that most of hydrogen atoms are associated with
the HIFP in the a-alloys. For the relaxation parameters of the HIFP, values of 1/τ0 fall in the range expected for a simple relaxation process for
a-Zr60 Cu40−y Al y (y = 0, 10) and a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3), but are extremely high for a-Zr50 Cu50 and a-Zr40 Cu60 , where τ0 denotes
the pre-exponential factor of the relaxation time. These results are discussed in the light of the amorphous structures in the a-alloys.
(Received June 10, 2002; Accepted August 7, 2002)
Keywords: high-damping material, hydrogen internal friction peak, hydrogen diffusion, amorphous alloy, structural relaxation
102
∗ Graduate
Student, University of Tsukuba.
Mg
Mg-0.6%Zr
Fe-Cr-Al TiNiCu-Al-Ni
Al-Zn Fe-Co
grey cast
Mn-Cu-Al
Ni
iron(high C)
1
a-Zr60 Cu30Al10 (H10 )
Fe
10
grey cast iron
12Cr-steel
10-2
-1
AZ81A
10-1
Q
Future space development project may demand a highstrength and high-damping material working near and below
room temperatures (RT), because isolation of precision instruments from strong mechanical vibration during launching
and a suppression of mechanical vibrations of a space station
may be one of critical issues. The demand for such a material
working near and above RT may be urgent for smart precision machinery too. Figure 1 shows a specific damping index
or the internal friction vs. tensile strength map, where various
metallic materials are classified into three groups, the high-,
intermediate- and low-damping materials. The three lines are
drawn to guide eyes. For the high-damping materials, one can
see that the internal friction shows the general trend of a decrease with increasing tensile strength and no high-damping
materials with tensile strength beyond 1 GPa are found except
for hydrogenated amorphous alloys.1) It is known that most of
amorphous (a-) alloys show the mechanical responses such as
high strength, large elastic strain and low Young’s modulus,
indicating that they are tough and flexible. However, the internal friction, Q −1 , in a-alloys below the glass transition temperature is as low as that in the low- or intermediate-damping
materials.
Since the hydrogen internal friction peak (HIFP) in
hydrogen-charged a-alloys was found by Berry et al.,2) much
effort has been devoted to the subject. The pronounced HIFP
can be observed in the a-alloys which contain much hydrogen in solution, where the anelastic reorientation relaxation
of hydrogen in a-alloys is responsible for the HIFP in most
a-alloys.2–14) A recent review for the HIFP in a-alloys com-
Specific Damping Index (%)
1. Introduction
100
SUS304
S95C
10-3
Al cast alloy
bronze
-1
10
102
brass
103
Tensile Strength / MPa
Fig. 1 A specific damping index or internal friction (Q −1 ) vs. tensile
strength map. The “specific damping index” is the ratio of the energy
dissipated to the maximum stored energy when expressed as a percentage.
piles the Tp vs. Q −1
p data reported for metal-metal a-alloys
and metal-metalloid a-alloys, where Tp and Q −1
p denote the
temperature and the height of the HIFP, respectively.15) As reported in Ref. 15), a bird’s eye view of the whole data shows
two groups, the Pd-based metal-metalloid a-alloys as the low
Tp group and the other metal-metal and metal-metalloid aalloys as the high Tp group, with exception for a-Zr50 Cu50 12)
and a-Zr40 Cu60 .16) The well-known general trend of the decrease in Tp with increasing Q −1
p is believed to reflect that
−1
Q p increases and the activation enthalpy for the hydrogen
Hydrogen Internal Friction Peak in Amorphous Zr–Cu–Al–Si Alloys
diffusion in a-alloys decreases with increasing hydrogen concentration, C H , for most cases. The fact that the Tp vs.
Q −1
p data observed for various a-alloys fall on the limited
regions suggest that the local atomic structures observed by
a hydrogen atom are not so different among the various aalloys which can store hydrogen in solution as mentioned in
Ref. 15).
On the other hand, as mentioned in Ref. 15), Tp and Q −1
p of
the HIFP in a-Zr50 Cu50 12) and a-Zr40 Cu60 16) are, in general,
higher than those found in the high Tp group.
A recent work on the hydrogenated a-Ti50 Cu50 and aZr50 Cu50 indicates that the local strain around a hydrogen
atom in the a-alloys is highly anisotropic.17) This fact may be
responsible for the high-Q −1
p found for the HIFP in Zr50 Cu50
and Zr40 Cu60 a-alloys, and provide the evidence that the
stress-induced redistribution of hydrogen atoms gives rise the
HIFP in the a-alloys. Then one may expect that the Zr–Cu aalloys are potential materials with the high-strength and high−2
damping performance, because Q −1
p falls in the range of 10
and Tp may be tailored by a control of diffusion rate of hydrogen atoms.
As the first step, we investigated the HIFP in one of new
metallic glasses, a-Zr60 Cu30 Al10 18) as shown in Fig. 11) and
that in a-Zr40 Cu50 Al10 . It is found that Tp is higher for aZr40 Cu50 Al10 than for a-Zr60 Cu30 Al10 . The fact that the HIFP
in the a-alloys is observed as a very broad peak indicates that
the redistribution of hydrogen atoms for the anelastic relaxation may take place by migrations of hydrogen atoms threading through various tetrahedral sites.19–22) That is, in the latertransition-metal/early-transition-metal a-alloy, a-Az B1−z , the
maximum hydrogen content in the Am B4−m tetrahedral sites,
∆C z,m , may be given by,
∆C z,m = f 0 [4!/m!(4 − m)!]z m (1 − z)4−m
(1)
where the alloys are assumed to be structurally isomorphic and chemically random and f 0 = 1.6 at z = 0.5.21)
Equation (1) predicts that most of hydrogen atoms may occupy the Zr4 sites in the C H range below about 20 at% for
a-Zr60 Cu30 Al10 and below about 4 at% for a-Zr40 Cu50 Al10 .
After eq. (1), the representative migration path of hydrogen
atoms responsible for Tp inevitably threads through the (Cu
and Al)4 sites in a-Zr40 Cu50 Al10 but it is not the case in aZr60 Cu30 Al10 at the low C H range. It is reported that the HIFP
in a-Pd–Si is associated with reorientation of hydrogen atoms
trapped by silicon atoms.10) We surmise that Tp of the HIFP in
a-Zr40 Cu50 Al10 may be tailored by addition of silicon to the
a-alloy. In the present paper, we pursued this issue.
For the anelastic reorientation relaxation of hydrogen in
a-alloys, however, the underlying process is only partly understood as yet.2–16) One reason is that the observed relationship between Tp and C H and that between Q −1
p and C H show
variety among various a-alloys, suggesting that the detailed
anelastic process for the HIFP is a function of the chemical
composition of a-alloys. For the later-transition-metal/earlytransition-metal a-alloys, the anelastic reorientation of hydrogen atoms sitting in tetrahedral sites may be responsible
for the HIFP.5, 7, 8, 11, 12) Since the HIFP in the later-transitionmetal/early-transition-metal a-alloys is, in general, observed
as a very broad peak, the relaxation time, τ , for the anelastic
2663
process should have a wide distribution. One may, however,
define the representative relaxation time which explains Tp of
the HIFP as,
1/τ = 1/τ0 exp(−E/kT ),
(2)
where 1/τ0 is the frequency factor, E is the activation energy,
k is the Boltzmann factor and T is temperature. A value of
1/τ0 reported for the HIFP in a-Zr60 Ni40 ,9) a-Ti50 Cu50 ,11) aZr50 Cu50 ,12) and a-Zr40 Cu60 16) is as high as 1014 –1016 s−1 ,
suggesting that a migration distance of hydrogen atoms for
the HIFP may be the order of atomic distance, and the entropy
factor for the migration may not be negligible in the a-alloys.
As already mentioned, however, a migration distance of hydrogen atoms for the HIFP in a-Zr40 Cu50 Al10 appears to be
longer than that in a-Zr60 Ni40 , a-Ti50 Cu50 , a-Zr50 Cu50 , and aZr40 Cu60 . This issue is also important for tailoring Tp of the
HIFP, and pursued here too.
2. Experimental
Amorphous (a-) Zr60 Cu40−y Al y (y = 0, 10), a-Zr50 Cu50 ,
a-Zr40 Cu60 and a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3) alloy ribbons about 30 µm thick and 1 mm wide were prepared by
melt spinning in a high-purity Ar gas atmosphere and checked
by the conventional θ − 2θ scan X-ray diffraction using the
Cu–Kα radiation. The specimen surfaces are polished mechanically in water avoiding heating up during polishing to
remove a surface layer and to smooth out. Hydrogen charging was made electrolytically in 0.1 N H2 SO4 at RT. A hydrogen charged specimen was aged for one day to a few days
in the temperature range between 300 K and 330 K to homogenize the hydrogen distribution in the specimen. The internal friction, Q −1 , was measured in the temperature range between 80 K and 380 K by means of the vibrating reed method
working at about 200 Hz and strain amplitude of 10−6 . The
internal friction measurements were conducted for all the aalloy specimens mentioned above in order to pursue the relationship between the anelastic process for the HIFP and the
chemical composition of a-alloys. On the other hand, tensile tests of a-alloy specimens were made for a-Zr60 Cu30 Al10
and a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3) specimens to pursue
the high-strength performance. Tensile tests were conducted
at RT by using a hand made apparatus oriented for a thin
tape which is similar to the tensile test apparatus reported in
Ref. 23). After the Q −1 measurements or the tensile tests,
the specimen was subjected to the thermal degassing in a vacuum to measure the hydrogen concentration, C H , where the
calibration of thermal degassing was made by using commercial TiH2 powder. See Ref. 16) for details of the thermal
degassing.
3. Results
Figure 2 shows examples of the X-ray diffraction
(XRD) spectra observed for a-Zr40 Cu49 Al10 Si1 and aZr40 Cu47 Al10 Si3 in the as-quenched state. The detection of
the XRD reflections from crystalline (c-) Si, Zr5 Si3 , CuZr2 Si4
and unknown c-phase(s) for the a-Zr40 Cu47 Al10 Si3 specimen
indicates that the addition of silicon by 3% decreases considerably the glass forming ability of a-Zr40 Cu50 Al10 . In con-
2664
H. Mizubayashi, Y. Ishikawa and H. Tanimoto
50000
counts
Stress / GPa
2
3
2
1
a-Zr40Cu49Al10 Si1
Intensity
2
2
1: c-Si
2: c-Zr5 Si 3
3: c-CuZr2 Si4
: no charge
: 0.9 %H
: 7.2 %H
: 9.8 %H
: 10.4 %H
: 17.1 %H
Zr60Cu 30 Al10 (H)
1
(a)
0
2
2
Zr40Cu 49Al10 Si1(H)
(b)
30
40
50
60
2
Fig. 2 The XRD spectra observed for a-Zr40 Cu49 Al10 Si1 and a-Zr40 Cu47 Al10 Si3 . Vertical arrows 1 to 3 denote the 2θ values of the XRD reflections
expected for crystalline Si, Zr5 Si3 and CuZr2 Si4 , respectively.
Stress / GPa
a-Zr40 Cu 47Al10Si 3
1
0
0
heating rate = 1 K/s
no charge
4.5at%
5.5at%
5.9at%
17.1at%
1
2
3
4
5
-dC H /dt (arbitrary unit)
Strain (%)
Zr60Cu 30 Al10
CH = 13.2 at%
Fig. 4 Examples of the tensile tests of (a) a-Zr60 Cu30 Al10 1) and (b)
a-Zr40 Cu49 Al10 Si1 specimens at RT before or after hydrogen charging.
Zr40 Cu 50 Al10
CH = 13.0 at%
Zr40 Cu 49 Al10 Si1
CH = 13.4 at%
400
600
800
1000
T/K
Fig. 3 Examples of the thermal degassing spectrum observed for the hydrogen charged a-Zr60 Cu30 Al10 , a-Zr40 Cu50 Al10 and a-Zr40 Cu49 Al10 Si1
specimens.
trast, no detection of a crystalline phase for a-Zr40 Cu49 Al10 Si1
can be seen in Fig. 2.
Figure 3 shows examples of the thermal degassing spectrum observed for the hydrogen charged a-Zr60 Cu30 Al10 , aZr40 Cu50 Al10 and a-Zr40 Cu49 Al10 Si1 specimens, where C H is
about 13 at%. The hydrogen thermal degassing (HTD) from
the a-Zr60 Cu30 Al10 specimen with C H of 13.2 at% is observed
above about 800 K after the crystallization, where the HTDs
from α-Zr and Zr hydrides16) are expected. The thermal
degassing spectrum from the a-Zr40 Cu50 Al10 specimen with
C H of 13.2 at% and that from the a-Zr40 Cu49 Al10 Si1 specimen with C H of 13.4 at% are similar to that observed for aZr40 Cu60 specimen with comparable C H ,16) where the HTD
around 640 K (the HTD around 660 K with the heating rate of
1.4 K/s in Ref. 16) is surmised that from one part of the Zr4
sites in the a-alloys. No HTD around 640 K observed for the
a-Zr60 Cu30 Al10 specimen indicates that the site energy for hydrogen of the Zr4 sites in the a-Zr60 Cu30 Al10 specimen with
C H of 13.2 at% is comparable with the enthalpy of solution
in α-Zr (−64 kJ/mol H).16) It is noted that after eq. (1), the
Zr4 sites in a-Zr60 Cu30 Al10 can store hydrogen by 20.7 at%,
and the Zr4 and Zr3 (Cu, Al)1 sites in a-Zr40 Cu50 Al10 can store
hydrogen by 4.1 at% and 24.5 at%, respectively.
Figures 4(a) and (b) show examples of the tensile tests of
a-Zr60 Cu30 Al10 and those of a-Zr40 Cu49 Al10 Si1 specimens at
RT before or after hydrogen charging, respectively. For aZr60 Cu30 Al10 specimens, strain shows a nonlinear increase
with increasing stress and the feature of the stress vs. strain
curve remains unchanged after hydrogen charging for C H
below 20 at%. The fracture strength, σf , of a-Zr60 Cu30 Al10
specimens increases, in general, with increasing C H . For aZr40 Cu49 Al10 Si1 , the stress vs. strain data show an inverseS like curve and the feature of the stress vs. strain curve
remains unchanged after hydrogen charging for C H below
20 at%. It is not shown here but the inverse-S like stress vs.
strain curve is commonly observed for a-Zr40 Cu50−x Al10 Six
(x = 0, 1, 3). Figure 5 shows σf of a-Zr60 Cu30 Al10 1) and aZr40 Cu50−x Al10 Six (x = 0, 1, 3) as a function of C H . For C H
below 20 at%, σf of a-Zr60 Cu30 Al10 , a-Zr40 Cu50 Al10 and aZr40 Cu49 Al10 Si1 are similar to each other, where σf increases
from about 1.5 GPa in the as quenched state to about 2 GPa
at C H of 20 at%. On the other hand, σf of a-Zr40 Cu47 Al10 Si3
is lower by about 0.5 GPa than σf of other a-alloys mentioned
above, probably due to precipitation of c-Si, c-Zr5 Si3 and cCuZr2 Si4 . In other words, dissolved Si of 1% hardly modifies the mechanical property of a-Zr40 Cu50 Al10 . The σf data
shown in Fig. 5 indicate that a-Zr60 Cu30 Al10 , a-Zr40 Cu50 Al10
Hydrogen Internal Friction Peak in Amorphous Zr–Cu–Al–Si Alloys
2665
f
/ GPa
2
1
Zr 60 Cu30 Al 10
Zr 40 Cu50 Al 10
Zr 40 Cu49 Al 10 Si1
Zr 40 Cu47 Al 10 Si3
0
0
10
20
C H (at%)
Fig. 5 The fracture strength, σf , of a-Zr60 Cu30 Al10 ,1) a-Zr40 Cu50 Al10 ,
a-Zr40 Cu49 Al10 Si1 and a-Zr40 Cu47 Al10 Si3 observed at RT is plotted
against C H .
and a-Zr40 Cu49 Al10 Si1 specimens show the high-strength performance mentioned in Fig. 1 for C H below 20 at%. In other
words, the elastic strain attained before the fracture of the
specimens is about 2% in the as quenched state and tends to
increase after hydrogen charging for C H below 20 at% (see
Fig. 4). On the other hand, the elastic strain attained before
the fracture of the specimens decreases after hydrogen charging for C H beyond several tens at%, i.e., these a-alloys become brittle for C H beyond several tens at% (not shown here).
Figures 6(a) to (c) show examples of the HIFP observed
in a-Zr60 Cu30 Al10 ,1) a-Zr40 Cu50 Al10 1) and a-Zr40 Cu49 Al10 Si1
specimens, respectively, where the measurement frequency is
about 200 Hz. It is noted that the aging temperature after hydrogen charging was about 330 K for a-Zr60 Cu30 Al10 and aZr40 Cu50 Al10 and about 300 K for a-Zr40 Cu49 Al10 Si1 , respectively. As already mentioned, the HIFP in a-Zr–Cu(Al) is ob−2
served as a very broad peak with Q −1
p of the order of 10 , indicating that the high-damping performance can be expected
in a wide temperature range more than 100 K. In Fig. 6(a),
for a specimen with C H of 6.1 at%, a heating run from 80 to
380 K after hydrogen charging and a cooling run after heating
−2
to 380 K are indicated by arrows, where Q −1
p of 5.5 × 10
observed in the as charged state decreases to about 4 × 10−2
after heating to 380 K. In contrast, for a specimen with C H of
−2
observed in the as charged state
13.2 at%, Q −1
p of 1.4 × 10
remains almost unchanged after heating to 380 K. As seen
in Fig. 6(a), the higher the Q −1
p in the as charged state is, the
−1
larger the decrease in Q p after heating to about 380 K is. The
decrease in Q −1
p for the HIFP in a-Zr60 Cu30 Al10 is not due to
degassing of hydrogen but due to the hydrogen induced structural relaxation (HISR) reported for a-Zr40 Cu60 .16) It is noted
that an a-Zr60 Cu30 Al10 with C H of 4.5 at% has been annealed
at 600 K for 2 hours in a vacuum prior to hydrogen charging.
For the pre-annealed specimen with C H of 4.5 at%, although
−2
Q −1
p in the as charged state is as high as 3×10 , a decrease in
Q −1
p after heating to 380 K is smaller than for the as quenched
specimens showing comparable Q −1
p , indicating that an effect
of the HISR decreases in the pre-annealed specimen. The observed features for the HIFP in a-Zr40 Cu50 Al10 shown in Fig.
Fig. 6 Examples of the HIFP observed in (a) a-Zr60 Cu30 Al10 ,1) (b)
a-Zr40 Cu50 Al10 1) and (c) a-Zr40 Cu49 Al10 Si1 specimens.
6(b) are similar to those for the HIFP in a-Zr60 Cu30 Al10 except that Tp is higher for the HIFP in a-Zr40 Cu50 Al10 than
in a-Zr60 Cu30 Al10 when they are compared at the same C H ,
−2
are found
and no specimens showing Q −1
p beyond 4 × 10
in a-Zr40 Cu50 Al10 . The observed features for the HIFP in aZr40 Cu49 Al10 Si1 shown in Fig. 6(c) are similar to those for
the HIFP in a-Zr40 Cu50 Al10 except that Tp is higher for the
HIFP in a-Zr40 Cu49 Al10 Si1 than in a-Zr40 Cu50 Al10 when they
are compared at the same C H . The decrease in Q −1
p due to
the HISR during heating to 380 K is considerably larger for
a-Zr40 Cu49 Al10 Si1 than for a-Zr40 Cu50 Al10 , because the aging temperature of about 300 K after hydrogen charging for
a-Zr40 Cu49 Al10 Si1 is lower than that of about 330 K for aZr40 Cu50 Al10 . Q −1
p observed after heating to 380 K for aZr40 Cu49 Al10 Si1 is about 1 × 10−2 for the C H range shown
in Fig. 6(c).
Figure 7 shows the Tp vs. C H data found for various a-Zr–
Cu(Al, Si) alloys. Tp shows variety as a function of the chemical composition of a-alloys in the C H range below 20 at%, and
decreases to about 220 K with increasing C H . The Tp vs. C H
data shown in Fig. 7 may be classified into three groups, aZr40 Cu49 Al10 Si1 and a-Zr40 Cu47 Al10 Si3 as the high-Tp group,
a-Zr40 Cu60 and a-Zr40 Cu50 Al10 as the intermediate-Tp group
and a-Zr60 Cu40 , a-Zr60 Cu30 Al10 and a-Zr50 Cu50 as the low-Tp
group. It is noted that Tp of the HIFP in a-Zr50 Cu50 is, in gen-
2666
H. Mizubayashi, Y. Ishikawa and H. Tanimoto
Table 1 Relaxation parameters of the hydrogen internal friction peak.
Specimen
1/τ0∗1 (s−1 )
E ∗1 (eV∗2 )
Reference
a-Zr60 Cu40 (H6.7 )
a-Zr60 Cu30 Al10 (H10.2 )
a-Zr60 Cu30 Al10 (H2.0 )
a-Zr50 Cu50 (H5.3 )
a-Zr50 Cu50 (H5 –H20 )
a-Zr40 Cu60 (H5.7 –H20.9 )
a-Zr40 Cu55 Al5 (H5.7 )
a-Zr40 Cu50 Al10 (H3.8 )
a-Zr40 Cu49 Al10 Si1 (H13.1 )
1.5 × 1011
0.34
0.33
0.36
0.68
0.72–0.63
0.73–0.58
0.56
0.59
0.47
present
present
present
present
(12)
(16)
present
present
present
5.2 × 1010
2.9 × 1010
6.6 × 1015
9 × 1016
2.5 × 1014
1.8 × 1012
1.5 × 1012
3.0 × 1010
∗1 τ
0 and E are a pre-exponential factor and the activation enthalpy for the
relaxation time.
∗2 1 eV = 1.602 × 10−19 J.
4. Discussion
Fig. 7 The Tp vs. C H data found for various Zr–Cu(Al, Si) a-alloys, where
the data found in a-Zr60 Cu40 and a-Zr60 Cu30 Al10 ,1) a-Zr50 Cu50 12) and
a-Zr40 Cu60 16) are also shown.
eral, higher than that found in various a-alloys except a-Zr–Cu
alloys,15) indicating that Tp of the HIFP in a-Zr40 Cu49 Al10 Si1
and a-Zr40 Cu47 Al10 Si3 shows a breakthrough for an elevation
of Tp of the HIFP in a-alloys.
Figures 8(a) to (d) show the Q −1
p vs. C H data found for
a-Zr60 Cu40−y Al y (y = 0, 10),1) a-Zr50 Cu50 ,12) a-Zr40 Cu60 16)
and a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3), respectively. As seen
in Fig. 8(a), one part of a-Zr60 Cu40−y Al y (y = 0, 10) speci−2
at the as charged
mens show very high Q −1
p beyond 3 × 10
state. On the other hand, no specimens show Q −1
p beyond
3 × 10−2 after aging at 350 K for 1 day following hydrogen
charging (not shown here). In Fig. 8(a), the dashed line 1
is drawn to guide eyes for Q −1
p after the HISR below about
appears
to
increase
monotonously with increas380 K. Q −1
p
ing C H for C H below 20 at%, where the maximum hydrogen
content in the Zr4 tetrahedral sites in a-Zr60 Cu40−y Al y is estimated to be 20.7 at% after eq. (1). In contrast, for a-Zr50 Cu50
shown in Fig. 8(b), the Q −1
p vs. C H data shows a camel’s
humps like change as a function of the site occupation mentioned for eq. (1) (see Ref. 12) for details). the Q −1
p vs. C H
data for a-Zr40 Cu60 shown in Fig. 8(c) also appear to show a
camel’s humps like change as a function of the site occupation mentioned for eq. (1).16) In contrast, the Q −1
p vs. C H data
for a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3) shown in Fig. 8(d) are
similar to those for a-Zr60 Cu40−y Al y (y = 0, 10) shown in
Fig. 8(a) rather than those for a-Zr40 Cu60 shown in Fig. 8(c),
except that Q −1
p for a-Zr40 Cu47 Al10 Si3 is, in general, about
one half of that for a-Zr40 Cu50−x Al10 Six (x = 0, 1).
Figure 9 shows the Arrhenius plot for the HIFP observed
in various a-alloys, and the relaxation parameters, 1/τ0 and
E, determined are compiled in Table 1, where τ0 and E are
a pre-exponential factor and the activation enthalpy for the
relaxation time, respectively, and f is a measurement frequency. In Table 1, one can see that values of 1/τ0 found
for a-Zr50 Cu50 and a-Zr40 Cu60 are as high as 1014 to 1016 s−1 ,
and those found for other a-alloys are of a value expected for
a simple relaxation process.
Feasibility of the hydrogenated a-alloys as a high-strength
and high-damping material will be discussed at first. The
tensile test data shown in Fig. 5 indicate that σf increases
from about 1.5 GPa in the as quenched state to about 2 GPa
at C H of 20 at% for a-Zr60 Cu30 Al10 and a-Zr40 Cu50−x Al10 Six
(x = 0, 1). The Q −1 performance required for the high
σf range is about 1 × 10−2 after Fig. 1. In Fig. 8(a) and
−2
8(d), the Q −1
may be attained around
p of about 1 × 10
C H of 10 at% for a-Zr60 Cu30 Al10 and a-Zr40 Cu50−x Al10 Six
(x = 0, 1) specimens after HISR. Referring to Fig. 7, Tp
at C H of 10 at% is 310 K, 270 K and 220 K with the measurement frequency, f , of about 200 Hz for a-Zr40 Cu49 Al10 Si1 ,
a-Zr40 Cu50 Al10 and a-Zr60 Cu30 Al10 , respectively. Since
the HIFPs in a-Zr40 Cu49 Al10 Si1 , a-Zr40 Cu50 Al10 and aZr60 Cu30 Al10 are very broad as seen in Fig. 6(a) to (c), the
working temperature range is several tens degrees around Tp .
For the working frequency, the relaxation parameters listed
in Table 1 give that values of Tp expected for f of 10 Hz
and 100 kHz are 170 K and 339 K for a-Zr60 Cu30 Al10 (H10.2 )
and 273 K and 506 K for a-Zr40 Cu49 Al10 Si1 (H13.1 ), respectively. Values of Tp for a-Zr40 Cu50 Al10 (H10 ) may be intermediate between those mentioned for a-Zr60 Cu30 Al10 (H10.2 )
and a-Zr40 Cu49 Al10 Si1 (H13.1 ). These parameters indicate that
the hydrogenated a-Zr40 Cu49 Al10 Si1 , a-Zr40 Cu50 Al10 and aZr60 Cu30 Al10 are a candidate as a high-strength and highdamping material with a tuned performance. Further, one
may expect that a composite material composed of these aalloys can serve a high-damping performance in a wide temperature range or a wide frequency range.
The physical properties other than the high-strength and
high-damping performance will be discussed below. For most
a-alloys, strain shows a nonlinear increase with increasing
stress as mentioned for a-Zr60 Cu30 Al10 in Fig. 4(a), reflecting
that the stress-induced internal rearrangement of atoms can be
allowed.24, 25) It is believed that the amorphous structure of the
a-alloy is composed of a low density region and a high density region reflecting the density fluctuation, and the stressinduced internal rearrangement of atoms started in the low
density regions proceeds resulting in the nonlinear increase in
strain with increasing stress.25) For most a-alloys, it is also believed that the stress-induced internal rearrangement of atoms
Hydrogen Internal Friction Peak in Amorphous Zr–Cu–Al–Si Alloys
2667
6
: a-Zr 50 Cu 50
: a-Zr60 Cu40
: a-Zr60 Cu30 Al10
5
3
2'
-1
10 Q p
3
2
2
2
2
10 Q p
-1
4
2
1
1
(a)
1
0
0
10
20
(b)
0
0
30
10
20
30
C H (at%)
C H (at%)
: a-Zr 40 Cu 50 Al 10
: a-Zr 40 Cu 49 Al 10 Si 1
: a-Zr 40 Cu 47 Al 10 Si 3
2
2
10 Q p
-1
3
1
4
5
0
0
10
(d)
20
30
C H (at%)
Fig.
Fig. 9
8 The Q −1
vs. C H data observed for (a) a-Zr60 Cu40−y Al y
p
a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3). The dashed lines 1, 4 and
and 2 , and Ref. 16) for the dashed lines 3, 3 and 3 .
The Arrhenius plot for the HIFP observed in the various a-alloys.
proceeds to the shear band for further elevated stresses resulting in the plastic deformation.26) On the other hand, one may
expect the saturation of the nonlinear increase in strain be-
(y =
(b) a-Zr50 Cu50 ,12) (c) a-Zr40 Cu60 16) and (d)
5 are drawn to guide eyes. See Ref. 12) for the dashed lines 2
0, 10),1)
low the elastic limit when the low density regions are isolated
from each other. The inverse-S like stress vs. strain curves observed for a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3) (see Fig. 4(b))
possibly suggest that the low density regions are embedded
in the high density matrix for the amorphous structure of the
alloys. Further speculation is, however, premature without
more extended data.
As mentioned for Fig. 7, Tp of the HIFP for a-Zr50 Cu50
and that for a-Zr40 Cu60 are, in general, higher than those
found in the high Tp group compiled in Ref. 15), here aZr60 Cu40−y Al y (y = 0, 10) may be classified into the high
Tp group in Ref. 15). On the other hand, Tp of the HIFP
for a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3) is higher than Tp for
a-Zr50 Cu50 and a-Zr40 Cu60 . That is, one can see the following order, (Tp for a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3))>(Tp for
a-Zr50 Cu50 and a-Zr40 Cu60 )>(Tp for a-Zr60 Cu40−y Al y (y =
0, 10)), in the low C H range, and that Tp decreases to about
220 K with increasing C H . For the relaxation parameters in
the low C H range listed in Table 1, 1/τ0 is comparable between
a-Zr40 Cu50−x Al10 Six (x = 0, 1, 3) and a-Zr60 Cu40−y Al y
(y = 0, 10) and E is higher for a-Zr40 Cu50−x Al10 Six (x =
0, 1, 3) than a-Zr60 Cu40−y Al y (y = 0, 10). We surmise
that the characteristic amorphous structure supposed for a-
2668
H. Mizubayashi, Y. Ishikawa and H. Tanimoto
Zr40 Cu50−x Al10 Six (x = 0, 1, 3) is responsible for the higher
value of E, where the migration of hydrogen atoms for the
HIFP around Tp takes place through the high density regions.
For the effect of Si addition to a-Zr40 Cu50 Al10 , it is observed that 1/τ0 found for a-Zr40 Cu49 Al10 Si1 (H13.1 ) is lower
than that for a-Zr40 Cu50 Al10 (H3.8 ). It is observed for the
HIFP in a-Zr50 Cu50 12) and a-Zr40 Cu60 16) that 1/τ0 remains almost unchanged and E decreases with increasing C H . We
surmise that the increase in Tp found for a-Zr40 Cu49 Al10 Si1
is mainly associated with the decrease in 1/τ0 . Such a decrease in 1/τ0 can be expected when trapping of hydrogen
atoms occurs during migration of hydrogen atoms for the
HIFP. However, a simple trapping of hydrogen atoms by Si
atoms in solution may not explain the decrease in 1/τ0 observed, because C H of 10 at% is considerably higher than Si
content of 1%. On the other hand, it can be seen that in Fig.
−1
8(d), Q −1
p for a-Zr40 Cu47 Al10 Si3 is about one half of Q p
for a-Zr40 Cu49 Al10 Si1 , and in Figs. 6(b) and (c), the HIFP is
sharper for a-Zr40 Cu49 Al10 Si1 than a-Zr40 Cu50 Al10 . It is suggested that the amorphous structure of a-Zr40 Cu50−x Al10 Six
(x = 0, 1, 3) is modified as a function of Si content.
vs. C H data are a function of the chemical
The Q −1
p
composition of a-alloys as already reported,3–16) here aZr60 Cu40−y Al y (y = 0, 10) and a-Zr40 Cu50−x Al10 Six (x =
0, 1, 3) are birds of a feather, and a-Zr50 Cu50 and a-Zr40 Cu60
are another birds of a feather. For the HIFP due to the
Snoek relaxation process,27) the relaxation strength, SH , may
be given by,
SH = (Ω M/9 kT )
· [(λ1 − λ2 )2 + (λ2 − λ3 )2 + (λ3 − λ1 )2 ] · C H,S ,
(3)
where Ω is the mean atomic volume of an a-alloy, M denotes the Young’s modulus, and λ1 , λ2 and λ3 are the principal values of the strain ellipsoid for the elastic distortion
around a hydrogen atom. C H,S denotes the hydrogen concentration associated with the HIFP, where C H,S ≤ C H . The
= SH /2 is known for a single relaxrelationship of Q −1
p
ation process. For a multiple or distributed relaxation pro−1
cess, the relationship of Q −1
p < SH /2 is expected, and Q p
measures the constituent relaxation strength for a predominant process. As already mentioned for Fig. 8(a), one part
of a-Zr60 Cu40−y Al y (y = 0, 10) specimens show very high
−2
Q −1
at the as charged state, and the dashed
p beyond 3 × 10
−1
line 1 drawn for Q p after the HISR below 380 K shows a
moderate increase to about 1.5 × 10−2 at C H of 20 at%. It
is reported that a decrease in the specific volume due to the
crystallization is as low as 0.3% for a-Zr60 Cu30 Al10 ,28) where
interstices for the hydrogen sitting sites in for a-Zr60 Cu30 Al10
may be small. For such a case, one may expect that an elastic distortion around a hydrogen atom is as strong as resulting
in very high Q −1
p , and brings about the HISR at an elevated
temperature. The Q −1
p vs. C H data for a-Zr60 Cu30 Al10 after
the HISR show that C H,S increases with increasing C H for C H
below 20 at%. It is noted that a maximum hydrogen content
in the Zr4 sites in a-Zr60 Cu30 Al10 is estimated as 20.7 at% after eq. (1), suggesting that most of hydrogen atoms are associated with the HIFP in the a-alloy. In contrast, as seen in
−2
at the
Fig. 8(b), Q −1
p for a-Zr50 Cu50 remains below 3 × 10
as charged state, and the Q −1
p vs. C H data shows a camel’s
humps like change, where C H,S in eq. (3) is assumed to vary
as a function of the site occupation.12) That is, the site energy of, e.g. the Zr4 sites, shows a distribution reflecting the
fluctuation in the atomic structure, i.e. a Gaussian distribution, which hydrogen atoms occupy under nearest neighbor
blocking. The camel’s humps like change can be explained
by assuming that only hydrogen atoms sitting the sites with
the site energy near the chemical potential can contribute to
the HIFP. The Q −1
p vs. C H data for a-Zr40 Cu60 shown in Fig.
8(c) also appear to show a camel’s humps like change,16) except that one part of the specimens show very high Q −1
p be−2
−1
yond 3 × 10 . On the other hand, the Q p vs. C H data for aZr40 Cu50−x Al10 Six (x = 0, 1, 3) are similar to those found for
a-Zr60 Cu40−y Al y (y = 0, 10) rather than those observed for aZr50 Cu50 and a-Zr40 Cu60 . It is suggested that the amorphous
structure for a-Zr50 Cu50 and a-Zr40 Cu60 is different from that
for a-Zr60 Cu40−y Al y (y = 0, 10) and a-Zr40 Cu50−x Al10 Six
(x = 0, 1, 3). As already mentioned for Table 1, very high
values for 1/τ0 are found for the HIFP in a-Zr50 Cu50 and aZr40 Cu60 , suggesting that the entropy factor in the hydrogen
diffusion coefficient should be very high. We surmise that
very high values for 1/τ0 and the camel’s humps like change
found for a-Zr50 Cu50 and a-Zr40 Cu60 reflect the characteristics of the amorphous structure in the a-alloys. Further work
is now in progress to pursue this issue.
5. Conclusion
We investigated the HIFP in a-Zr60 Cu40−y Al y (y =
0, 10), a-Zr50 Cu50 , a-Zr40 Cu60 and a-Zr40 Cu50−x Al10 Six (x =
0, 1, 3). The tensile strength, σf , of a-Zr60 Cu40 Al10 , aZr40 Cu50 Al10 and a-Zr40 Cu49 Al10 Si1 increases from about
1.5 to 2 GPa with increasing C H to 20 at%. One part of aZr60 Cu40 Al10 , a-Zr40 Cu50 Al10 and a-Zr40 Cu49 Al10 Si1 speci−2
in the as hydromens show very high Q −1
p beyond 3 × 10
gen charged state, where the HISR proceeds above RT, suggesting that the elastic strain around hydrogen atoms is very
large in the a-alloys in the as-charged state. Q −1
p after the
HISR shows a moderate increase with increasing C H , about
1 × 10−2 at C H of 10 at%, suggesting that a-Zr60 Cu30 Al10 (H),
a-Zr40 Cu50 Al10 (H) and a-Zr40 Cu49 Al10 Si1 (H) after the HISR
are potential materials with a high-strength and high-damping
performance. Tp at 10 at%H is 310 K, 270 K and 220 K
with the measurement frequency of about 200 Hz for aZr40 Cu49 Al10 Si1 , a-Zr40 Cu50 Al10 and a-Zr60 Cu30 Al10 , respectively. It is indicated that Tp found for a-Zr40 Cu49 Al10 Si1
shows a breakthrough for an elevation of Tp of the HIFP in
a-alloys, and that a composite material composed of these aalloys can serve a high-damping performance in a wide temperature range or a wide frequency range.
The Q −1
p vs. C H data shows a camel’s humps like change
for a-Zr50 Cu50 and a-Zr40 Cu60 , suggesting that only one part
of hydrogen atoms can contribute to the HIFP. In contrast,
Q −1
p shows a monotonous increase with increasing C H for
C H below 20 at% for a-Zr60 Cu40−y Al y (y = 0, 10) and aZr40 Cu50−x Al10 Six (x = 0, 1, 3), suggesting that most of hydrogen atoms are associated with the HIFP in the a-alloys.
For the relaxation parameters of the HIFP, values of 1/τ0
Hydrogen Internal Friction Peak in Amorphous Zr–Cu–Al–Si Alloys
fall in the range expected for a simple relaxation process
for a-Zr60 Cu40−y Al y (y = 0, 10) and a-Zr40 Cu50−x Al10 Six
(x = 0, 1, 3), but are extremely high for a-Zr50 Cu50 and aZr40 Cu60 . As already mentioned, the addition of 1 at% Si to
a-Zr40 Cu50 Al10 causes a drastic increase in Tp . These results
are discussed in the light of the amorphous structures in the
a-alloys.
Acknowledgments
This work is partly supported by “New Protium Function
in sub-nano Lattice Matters” research project of a Grant in
Aid for Scientific Research from the Ministry of Education,
Science and Culture of Japan, and High Damping Materials
Project of “Research for the Future” of Japan Society for the
Promotion of Science.
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