How the tin concentration affects the interactions of intermetallic compounds of the cu-sn system with liquid gallium and a gallium-tin eutectic

Article abstract of DOI:10.1134/S0036023610080218

Interactions in the copper-gallium-tin ternary system are studied. New phase formation involves the step of dissolution of solid copper alloys in a liquid phase. The induction period of tin segregation in an autonomous phase depends on tin concentration in the feed. The formation of solid solution of gallium in tin is suggested Pleiades Publishing, Ltd., 2010.

Full text of DOI:10.1134/S0036023610080218

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2010, Vol. 55, No. 8, pp. 1275–1278. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © T.F. Grigor’eva, A.I. Ancharov, Kh.B. Manzyrykchy, K.D. Becker, V. epelak, A. P. Barinova, N. Z. Lyakhov, 2010, published in Zhurnal Neorganicheskoi
Khimii, 2010, Vol. 55, No. 8, pp. 1351–1354.
S
PHYSICOCHEMICAL ANALYSIS
OF INORGANIC SYSTEMS
How the Tin Concentration Affects the Interactions
of Intermetallic Compounds of the Cu–Sn System
with Liquid Gallium and a Gallium–Tin Eutectic
T. F. Grigor’evaa, A. I. Ancharova, Kh. B. Manzyrykchya, K. D. Beckerb,
V. S
epelakb, A. P. Barinovaa, and N. Z. Lyakhova
a Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch, Russian Academy of Sciences,
ul. Kutateladze 18, Novosibirsk, 630128 Russia
b Institute of Physical and Theoretical Chemistry, Braunschweig University of Technology, Braunschweig, Germany
Received April 3, 2009
Abstract—Interactions in the copper–gallium–tin ternary system are studied. New phase formation involves
the step of dissolution of solid copper alloys in a liquid phase. The induction period of tin segregation in an
autonomous phase depends on tin concentration in the feed. The formation of solid solution of gallium in tin
is suggested.
DOI: 10.1134/S0036023610080218
Interactions of copper powders with liquid gallium
This work studies the effect of the tin concentration
are known to yield CuGa2 immediately after they are in the initial Cu–Sn–Ga system on the formation rate
mixed [1–3]. In interactions of copper with twoꢀcomꢀ and composition of the second phase during the interꢀ
ponent gallium eutectics, the phase next after the action of mechanochemically synthesized intermetalꢀ
intermetallic compound should be formed of the eleꢀ lic compounds of the Cu–Sn system with liquid galꢀ
ments released from the eutectic:
Cu + (Ga + 12% Sn) CuGa2 + Sn,
Cu + (Ga + 24.5% In) CuGa2 + In.
It is pertinent that while the first phase (CuGa2
lium and a gallium–tin eutectic.
→
EXPERIMENTAL
→
Copper and tin intermetallic compounds of various
compositions were prepared mechanochemically
from appropriate mixtures of copper (PMSꢀ1) and tin
(POE) powders in an AGOꢀ2 waterꢀcooled highꢀ
power planetary mill in an argon atmosphere. The
drum volume was 250 cm3; ball diameter was 5 mm;
ball load: 200 g; sample size: 10 g; drum rotation speed
around a common axis: 1000 rpm.
Diffraction studies were carried out at the station of
the 4th SR channel of the VEPPꢀ3 storage ring at the
Siberian Synchrotron Radiation Center, the Institute
of Nuclear Physics, Siberian Branch of Russian Acadꢀ
emy of Sciences. A method was used where a thin
)
appears immediately after the components are mixed ,
the next phase requires a certain time to be formed,
that is, an induction period, after which its formation
occurs very rapidly. The induction period provides
enough time for most part of the CuGa2 to form [4].
Similar results were obtained in studying the interacꢀ
tion of a solid solution of tin in copper with a liquid
gallium–tin eutectic [5]. Presumably, the dissolution
of the solid phase in the liquid phase occurs after mixꢀ
ing a solid copper powder with the liquid eutectic, and
while CuGa2 starts to form immediately, tin piles up in
liquid gallium, thanks to its good solubility in liquid
gallium and the absence of intermetallic compounds
in the Ga–Sn system, and its crystallization starts only
as gallium is consumed in intermetallic compound
formation and once tin concentration in gallium
reaches a certain critical value. This suggestion being
true, an increase in tin concentration in the Cu–Sn–
Ga system would shorten the induction period and
increase the formation rate of the second phase.
(
0.4
×
0.4 mm) monochromatic beam ( = 0.3686 Å)
λ
passes through a thin layer of the material and gives a
diffraction pattern recorded by a flat area detector.
The diffracted beam was detected by a detector system
based on a MAR345 image plate detector (Marꢀ
research).
Precision diffraction studies were carried out at the
station of the 2nd SR channel using a parallel beam
mode. Such studies gain highꢀprecision data on the
unit cell parameters of test samples.
Calorimetric studies were perform on
NETZSCH STA 409 PC/PG instrument under an
The equilibrium phase diagram of the Ga–Sn sysꢀ
tem [6] teaches that, as tin is soluble in gallium, galꢀ
lium is soluble in tin, too. In this case, the second
phase can be formed as a solid solution.
a
1275

1276
GRIGOR’EVA et al.
The system having the least tin content of the solidꢀ
phase component (20%) was studied first. In agreeꢀ
ment with the previous suggestion, tin would pile up in
liquid gallium as the solid solution decomposition
progresses; its concentration would also increase on
account of gallium consumption in CuGa2 formation.
Sn301
In the case at hand, tin segregation into an autonoꢀ
mous phase occurred 30 h after the components were
mixed (Fig. 1). In the diffraction pattern, the tin phase
is represented by individual crystallites.
Sn 312
Though the reflections from tin are stronger than
the reflections from intermetallic compounds, tin
reflections are virtually undistinguishable from the
background when the diffraction pattern is integrated
over the diffraction angles. When integration is conꢀ
fined to the section in which a single reflection is posiꢀ
tioned rather than integrating over the entire range of
the angles, then this reflection will be well distinguishꢀ
able on the resulting diffraction pattern. When the tin
concentration in the Cu–Sn–Ga reaction system
becomes higher on account of using a gallium–tin
eutectic as the liquid phase (this means that tin is iniꢀ
tially contained in the liquid phase), the induction
period shortens considerably. In this case, tin is segreꢀ
gated into an autonomous phase 4 h after the compoꢀ
nents were mixed (Fig. 2).
Fig. 1. Fragment of the diffraction pattern from the prodꢀ
ucts of the interaction of the solid solution of gallium in tin
with liquid gallium. All unlabeled reflections belong to
intermetallic CuGa .
2
argon atmosphere in an Al2O3 crucible in the temperꢀ
ature range from room temperature to 290
°
С at a heatꢀ
ing rate of 20 K/min.
RESULTS AND DISCUSSION
Figure 3 displays data on the phase formation
dynamics gained by fitting the integrated intensities of
the relevant diffraction lines. This figure makes it clear
that the reflection intensity first rises very rapidly after
the induction period, but then drops also rapidly.
We have studied the interactions of samples having
compositions of Cu + 20% Sn (supersaturated solid
solution), Cu + 39% Sn (Cu3Sn), and Cu + 61% Sn
(
Cu6Sn5) with gallium and a gallium–tin eutectic of
composition Ga + 12% Sn. (Hereafter, all composiꢀ
tions are expressed in weight percent.)
In elucidating how the increasing tin concentration
in the solid phase component influences the process
270 min
250 min
260 min
I
I
I
211 Sn
110 CuGa2
Y
Y
Y
102 CuGa2
X
X
X
280 min
290 min
500 min
I
I
I
Y
Y
Y
X
X
X
Fig. 2. Fragments of the diffraction patterns from the products of the interaction of the solid solution of gallium in tin with the
gallium–tin eutectic recorded in various periods of time after mixing the components.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 8 2010

HOW THE TIN CONCENTRATION AFFECTS
1277
dynamics and the characteristics of the resulting
phases, we used intermetallic compounds prepared by
mechanochemical activation of copper with 39 and
61% tin as solid phase components.
I
, arb. units
1.0
0.8
0.6
0.4
0.2
The sample prepared by mechanochemical syntheꢀ
sis of the first composition is the Cu3Sn intermetallic
compound as identified by powder Xꢀray diffraction.
The sample prepared from a Cu + 61% Sn mixture,
comprises a single phase of the Cu6Sn5 intermetallic
compound. The steps of mixing the components to a
homogeneous material, applying this material to the
holder of the goniometer head, adjustment, and expoꢀ
sure take about 10 min. Even the first diffraction patꢀ
tern from the reaction products of Cu3Sn with the galꢀ
lium–tin eutectic measured after the component are
mixed, shows reflections from CuGa2 and tin (Fig. 4).
Over time, the tin reflections increase in number, size,
and intensity. In 10 h, all gallium from the eutectic
melt is consumed in CuGa2 formation and the chemiꢀ
cal interactions in the system stop. The interactions
1
2
CuGa2
Sn
1
2
0
0
200 400 600 800 1000 1200
, min
τ
Fig. 3. Phase formation dynamics during the Cu(Sn) +
(Ga–Sn) = CuGa + Sn reaction.
L
2
(а)
(b)
(c)
(d)
Fig. 4. Fragments of the diffraction patterns from the products of the interaction of a Cu + 39% Sn powder with the Ga + 12% Sn
eutectic: (a) the initial mechanochemically prepared intermetallic compound and (b) 10 min, (c) 1 h, and (d) 10 h after mixing
the components. All separate reflections belong to tin.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 8 2010

1278
mg
GRIGOR’EVA et al.
For all systems studied, powder Xꢀray diffraction
shows that the interaction products in the Cu–Sn–Ga
system are mixtures of CuGa2 and tin crystallites;
however, thermal studies of these products, where
chemical processes occurred at room temperature,
show that four endotherms on the relevant thermoanꢀ
alytical curves without considerable weight change
mW/mg
0.2
T, °C
300
250
200
150
100
50
1.0
0.1
DSC
0
0.5
0
(Fig. 5). The first appearing endotherm (~120 С) may
°
be associated with melting of the solid solution of galꢀ
lium in tin, and the further cascade with melting of tin
and structural alterations in CuGa2
–0.1
–0.2
–0.3
–0.4
TG
Т
.
To verify the suggestion about the occurrence of the
solid solution of gallium in tin in the product, we carꢀ
ried out precision measurements of the tin unit cell
parameter. The resulting values (
= 3.1697 0.0004 Å) slightly differ from tabulated
values ( = 5.831 = 3.181 Å).
а= 5.8063 0.0004 Å,
–0.5
с
а
Å, с
The aforementioned two facts allow us to suggest
that the solid solution of gallium in tin is formed as a
second phase during the interaction of copper–tin
alloys with gallium or the gallium–tin eutectic.
0
20
40
Time, min
60
Fig. 5. Thermoanalytical curves for a (Cu + 20% Sn) +
In summary, our studies have shown that the interꢀ
actions of copper and tin intermetallic compounds
with gallium and liquid gallium eutectics involve the
dissolution of the intermetallic compounds in the liqꢀ
uid metal. The induction period preceding tin segregaꢀ
tion into an autonomous phase shortens as the tin conꢀ
centration in the system increases to disappear when
the tin concentration reaches 40%. By the strength of
calorimetric and Xꢀray diffraction data, we suggest that
the second phase is the solid solution of gallium in tin.
(Ga + 12% Sn) sample.
produce the new phases of intermetallic CuGa2 and
tin. The constituent phases of the reaction product
have diverse particle sizes. Intermetallic CuGa2 has parꢀ
ticle sizes of at most 1 m; tin has far coarser particles.
µ
During the interaction of mechanochemically synꢀ
thesized Cu6Sn5 with the liquid gallium–tin eutectic
(that is, in a mixture having the highest tin concentraꢀ
tion), CuGa2 formation and tin segregation into an
autonomous phase also occur starting with the very
first minutes. The interaction rate is rather high, and
2 h after mixing no changes are observed in diffraction
patterns. Initially extended reflections transform durꢀ
ing the reaction to become separate and pointlike.
Because the reflections from CuGa2 form continuous
rings, we may infer that the crystallize sizes are less
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than 0.1 m.
µ
Thus, while tin concentrations in the system are
less than 20–30%, tin appears as an autonomous
phase after some induction period. The reflections
from both the intermetallic compound and tin have
high intensities. The increasing tin concentration in
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tallization of a tin phase to become undetectable under
our conditions. Reflections from both the tin phase
and the intermetallic phase decrease in size.
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RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 55 No. 8 2010