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International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 27
I J E N S August 2018 IJENS IJENS © -IJMME-5959-401806
A Study on the Effect of the Change of
Tempering Temperature on the
Microstructure Transformation of Cu-Ni-Sn
Alloy
Xuan Duong Pham1,*, Anh Tuan Hoang2,3, Duong Nam Nguyen1
1Vietnam Maritime University, Hai Phong, Vietnam 2 Ho Chi Minh city University of Transport, Ho Chi Minh, Vietnam
3 The Central Transport College VI, Ho Chi Minh, Vietnam
E-mail: phxduong@vimaru.edu.vn
Abstract— The copper alloys have been using in many
applications such as electrical devices, house wares, and others
due to their special properties. In this study, the changes in the
microstructure and hardness value of the alloy Cu-15Ni-8Sn after
heat treatment were investigated in the basis of Spinodal
decomposition theory and various analysis methods. After
quenching, an orderly microstructure (DO3) with low hardness
phase was formed in case of aging at 450oC within 2 hours. As a
result, an increase in the lubrication ability was shown for this
alloy. In addition, phase alpha that was considered as a solid
solution of Cu and Ni with high strength was formed by Spinodal
decomposition. Findings of this paper will orientate to produce a
new alloy for the fabrication of the small diesel engine bearing.
Index Term— Cu-15Ni-8Sn, bearing, Spinodal decomposition,
hardness
I. INTRODUCTION
Bearings are considered as the mechanical parts for
supporting the frictional portions in the vehicles, ships -
internal combustion engines (ICE) or compressors. The
bearing is a frictional bearing mechanical part, therefore, the
material for bearing fabrication has to meet the requirements
such as an embedding, a fatigue strength, a load and friction
resistant, and a wear resistant property [1]. Recently, based on
the demands of reducing the internal combustion engine size,
the bearing materials are usually used in order to meet the
higher loads with high speed, high friction, and high
temperature but low cost [2][3]. For this reason, bearing
materials grounded on the copper (Cu) system which contains
tin (Sn) as the main component instead of aluminum (Al)
system based materials. The bronze alloy contained up to
about 30% of Sn is considered as a kind of bearing material,
because up to about 14% of Sn content, the matrices of this
alloy are in the form of α+δ phase crystals [4]. This leads to
the load-resistant and the wear-resistant property. U.S. Pat.
No. 3,180,008 has presented a bearing material, the surface
layer of the multi-layer microstructure contains 2% to 10% of
In (Indium), 0.1% to 3% of Cu, 0.001% to 0.25% of Te
(Tellurium), 0.5% or less of Ag (silver) and/or 0.5% or less of
Sb (Antimon), and Pb (Lead) of remaining. However, about
5% to 35% of Pb and 20% or less of Sn, and Cu of remaining
to appear in the intermediate layer of the multi-layer
microstructure was shown [5]. This microstructure showed the
ability of high load resistance. The alloy contained 1% to 5%
or less of Ni (Nickel) and 0.5% to 3% or less of Sb, 8% to
20% or less of Pb and 4% to 10% by weight of Sn, and Cu of
remaining [6]. This material showed the incorporation of Sb,
the good combination between Ni and Pd, Cu to improve the
bearing performance. However, Ni and Sb are very expensive
thus this material is not suitable for the economy [7].
The materials for bearing fabrication have to meet the
requirements such as high fatigue strength, high seizure
resistance, high wear resistance (include abrasive wear,
adhesive wear, fatigue wear, corrosive wear erosive wear),
high conformability, high embed ability, high corrosion
resistance, high cavitation resistance, low cost and easy
fabrication [5][8][9].
With many advantages in terms of thermal conductivity,
corrosion resistance, durability, flexibility, lubricity, good
anti-friction, copper alloys are commonly used in a variety of
devices for silvering [8]. However, conventional copper alloys
work in heavy duty conditions, with low abrasion, corrosion,
and lubrication (such as swivel bits in drill bits), which work
after a short period of time [10]. These mechanical parts are
usually imported at very high cost or they are locally produced
but the quality is not guaranteed. Therefore, research on the
manufacture of copper alloys with good mechanical
properties, durability, and high abrasion resistant properties
are necessary [11][12]. One of the important requirements of
alloy for fabricating the bearing is to have a microstructure
consisting of high strength, high stiffness to load, alternating
with low hardness phase, which can wear out during work to
form a point containing lubricating oil [6]. The basis of high
durability copper alloy work in heavy load conditions is the
consequent application of Spinodal decomposition and phase
transformation during heat treatment [13]. Spinodal
microstructure are composed of a fine, homogeneous mixture
of two phases that form by the growth of composition waves
in a solid solution during a suitable heat treatment is called
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 28
I J E N S August 2018 IJENS IJENS © -IJMME-5959-401806
Spinodal decomposition [14]. The phases of the Spinodal
decomposition differ in composition from each other and from
the parent phase but have the same crystal microstructure as
the parent phase [15]. The fineness of Spinodal microstructure
is characterized by the distance between regions of identical
composition, which is of the order of 50 to 1000 Ao [16].
With Cu-15Ni-8Sn alloys, many studies have introduced
microstructure models and explored mechanisms for
increasing durability and phase formation during aging [17].
Observed six types of phases formed during heat treatment: on
granules and in γ (DO3) granules; γ discontinuous (column
type); structured order form of DO22 (CuxNi1-x)3Sn; Order
microstructure L12 (CuxNi1-x)3Sn; Modular type, resulting
from Spinodal spinning and δ-orthogonal phase (β-Cu3Ti)
with a = 0.451 nm, b = 0.538 nm, c = 0.427nm. The
microstructures observed in the alloys are different and shown
in Figure 1 [18].
Fig. 1. Effect of tempering temperature on the phase changes of Cu-15Ni-8Sn alloy
Most authors report that in Cu-Ni-Sn alloys studied, the
increase in durability is due to the contribution of Spinodal
decomposition [12][19]. In many alloys, the sign of the
Spinodal decomposition is found in the solid solution. Even
some studies have found traces of Spinodal formation that
formed prior to the formation of a solid solution and the
Spinodal decomposition formed during my process. However,
authors such as Miki and Ogino [20] have concluded that
Spinodal decomposition does not increase the hardness of Cu-
20Ni-8Sn and Cu-15Ni-8Sn alloys. The main role of durability
is the networking between the Spinodal region and the new
phase.
In this study, a study of microstructure transformation of
Cu-Ni-Sn alloy with the change of tempering temperature
resulting in the change in hardness was conducted in the basis
of Cu-15Ni-8Sn alloy.
II. MATERIALS AND METHODS
The study alloy has component as Table I.
Table I
Composition of alloy
Cu Ni Sn Fe Others
75.2 15.4 8.95 0.28 exist
After casting, the alloy is heated to 850oC to keep heat 3h
and cool in the water. Next, be aged at different temperatures
of 250oC; 300oC; 350oC; 400oC; 450oC and 500oC and in
different time intervals.The samples after the test were
hardness measurement, microscopic examination, microscope
photography, SEM analysis, thermal analysis, and analysis.
Experiments were conducted at the Vietnam Academy of
Sciences and the Hanoi University of Science Techno
III. RESULTS AND DISCUSSION
A. Microstructure
The microstructures show that in the post-casting state
(Figure 2), the alloy is strongly biased. Arranging rough
branches is not just the middle of the hat but even the seed.
Obviously, the composition part is very uneven. The alloy
hardness measured in the molding state is 110HB. Cu-Ni-Sn
alloys are uniformized by incubation at 850°C (Figure 3).
After 3h annealing at 850oC, tree branches were removed, the
alloys were completely homogeneous, with a particle size
smaller than that of the molding. This is the right
microstructure for the next spinodal transformation. The
hardness behind quenching is 98HB.
Fig. 2. Microstructure after casting
Fig. 3. Microstructure after annealing and quenching
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 29
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Fig. 4. Diagram of DSC analysis
To study the change in energy, to show the changes in
temperature change, the alloy after quenching was analyzed in
the laboratory of metal materials technology has the following
results:
From the thermal analysis diagram (Figure 4) found in the
temperature regions: 50oC; 418-482oC; 750-800oC the
appearance of the peak on the thermodynamic path. It can be
seen that from temperatures below 50oC began to show signs
of change, perhaps this is spinodal decomposition; Peaks in
the range of 418oC to 482oC correspond to the appearance of
the DO22 and L12 microstructures in the alloy, which are
formed when Sn is released from the Spinodal region,
preparing for new phase transformation. compared to theory,
with the results of the Roughen analysis and the results of the
change in temperature stiffness as discussed later. At 750-
800oC there is a discontinuous phase γ model with a DO3-like
microstructure.
Fig. 5. Microstructure after aging at 4500C (x13000)
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 30
I J E N S August 2018 IJENS IJENS © -IJMME-5959-401806
Fig. 6. Microstructure after aging at 4500C (x200000)
The SEM image at a low magnification of 13,000 times
(Figure 5) of the sample after aging at 450oC shows phase
separation, corresponding to the microstructure. The
microstructure (Figure 6) shows that the inner grain has a
smoothly distributed microstructure, indicating that it is the
microstructure of the Spinodal decomposition (Figure 5) while
the grain boundary is structured in layers.
Fig. 7. Microstructure of Cu-15Ni-8Sn alloy quenching at 850oC-2.5h; aging at
450oC-2h
Fig. 8. The hardness measurement of the phase of the Cu-15Ni-8Sn alloy after
quenching at 850oC-2.5h; aging at 550oC-2h
a
b
Hardness
test
Phase γ
Phase α
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 31
I J E N S August 2018 IJENS IJENS © -IJMME-5959-401806
c
d
e
f
g
h Fig. 9. Cu-15Ni-8Sn alloy after aging at 4500C within 2h
It can be seen from Figure 9 that SEM of Cu-15Ni-8Sn after
quenching uniformly and aging at 450oC within 2h (Fig. 9a
and Fig. 9b) with 13,000 of magnification shows the
microstructure of surface alloy in grain and grain boundaries.
However, SEM of Cu-15Ni-8Sn after quenching uniformly
and aging at 450oC within 2h (Fig. 9c to Fig. 9h ) with
150,000, 200,000, 13,000 of magnification shows the
microstructure of surface alloy in grain. The background SEM
shows the rich and poor microstructure of Sn which has the
Spinodal modules with the form of woven plaques. These
microstructures are evenly distributed on the ground, which is
the Spinodal structure of the Sn-rich microstructure. In order
to demonstrate the orderly microstructure, the Xray method
needs to be used.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 32
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Fig. 10. X-ray of Cu-15Ni-8Sn alloy after aging at 4500C within 2h
Position [°2Theta] (Copper (Cu))
10 20 30 40 50 60 70 80
Counts
0
400
1600
3600
6400
5.4
25 [
°];
16.2
9049 [
Å]
7.8
75 [
°];
11.2
2753 [
Å]
9.9
28 [
°];
8.9
0957 [
Å]
23.3
73 [
°];
3.8
0601 [
Å]
26.2
77 [
°];
3.3
9163 [
Å];
Cu N
i2 S
n
31.1
20 [
°];
2.8
7399 [
Å]
43.5
43 [
°];
2.0
7853 [
Å];
Cu
47.3
73 [
°];
1.9
1903 [
Å]
50.6
01 [
°];
1.8
0392 [
Å];
Cu
66.4
00 [
°];
1.4
0794 [
Å]
70.6
66 [
°];
1.3
3305 [
Å];
Cu N
i2 S
n
74.2
77 [
°];
1.2
7693 [
Å];
Cu
79.1
24 [
°];
1.2
0943 [
Å];
Cu N
i2 S
n
158R500
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 33
I J E N S August 2018 IJENS IJENS © -IJMME-5959-401806
From Figure 10, it can be seen the location of the line
appearance such as:
Outside the copper background, the second phase also is
detected corresponding to the compound formula CuNi2Sn
with small content.
The background includes bars:
d1(111)= 2,07853 A0, corresponding to angle 2 = 43,5430
d1(200) = 1,80392A0, corresponding to angle 2 = 50,6010
d1(220) = 1,27693 A0, corresponding to angle 2 = 74,2770
The second line system for the positions:
d2(111)= 3,39163 A0, corresponding to angle 2 = 26,2930
d2(200) = 1,3305A0, corresponding to angle 2 = 70,6660
d3(220) = 1,20943A0, corresponding to angle 2 = 79,9600
Besides three α phase bars, the apperance of and phase
with small content also can be seen in Figure 11. Moreover,
the transformation of orderly bridging phase ’ (DO22và L12)
with FCC to phase (CuxNi1-x)3Sn with DO3 (BCC) with
lattice parameter of 5,926 Å, the phase of with formula
(CuxNi1-x)3Sn and lattice parameter such as a= 4,51 Å ; b=5,39
Å ; c= 4,29 Å can be analyzed.
B. Hardness
Aging for longer periods of time and higher temperatures
indicate that there are black phases in the grain boundaries.
This phase is the γ shown in Figure 7 and Figure 8 and has a
lower hardness than the background phase. The measurement
of the phase hardness included base phase (light color with
high hardness, and black with lower hardness) is given in
Table 2.
Table II
Hardness of phase
From Table 2, it can be seen that the hardness of the base
phase α is very high on average 387 HV, the hardness of the
base phase α is much higher than the α background after
quenching. This proves that there may be a process of
Spinodal decomposition in the background, which increases
the hardness of the background. The relationship between Cu-
15Ni-8Sn alloy hardness and aging temperature is shown in
Figure 11, and between Cu-15Ni-8Sn alloy hardness and time
is shown in Figure 12.
Fig. 11. The relationship between Cu-15Ni-8Sn alloy hardness and
temperature
Fig. 12. The relationship between Cu-15Ni-8Sn alloy hardness and time
When aging at different temperatures, the hardness of the
alloy at temperatures of 250oC and 450oC is quite higher than
20HRC. The highest hardness at 350oC is 32HRC, equivalent
to C45 steel hardness in the well-tempered state, equivalent to
attainable strength up to 900MPa. This hardness value is quite
high compared to copper alloys in general. At this
temperature, the microstructure of the alloy has a net
microstructure between the Spinodal region and the new
phase. When aging at higher temperatures, coupled with the
presence of γ phase (black), the hardness of the alloy
decreased sharply.
The behavior of the hardness curved when increasing the
aging time is the same as when changing the temperature. Fix
aging at 350oC Cu-15Ni-8Sn alloys tested at 0.5h were given a
high hardness of 30HRC, however as the aging time is 1.5
hours, hardness is about 34HRC. This value is quite high and
suitable for many applications such as abrasion and high
elasticity mechanical parts. The aging time is about 2-3 hours
hardness slightly reduced but at about 3 to 3.5 hours hardness
increased and then dropped sharply. In the early stages, the
solid solution breaks down into fine, fine Spinodal regions
increase hardness. Thus, it may understand that, the longer the
22.6
26.4
32
24.123
11.1
0
5
10
15
20
25
30
35
250 300 350 400 450 500
Ha
rdn
ess,
HR
C
Temperature, oC
30 29.4
33.6
28.329.6
34 34.3
26.4
0
5
10
15
20
25
30
35
40
0.5 1 1.5 2 2.5 3 3.5 4
Har
dn
ess
, HR
C
Time, h
Phase Hardness (HV)
α
390 Average
387 382
387
γ
238 Average
235 230
237
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:04 34
I J E N S August 2018 IJENS IJENS © -IJMME-5959-401806
aging time is, the more increasing the Spinodal regions are,
and lead to increase the hardness. But if prolonged aging
occurs, when new phases appear, the hardness decreases. In
the basis of the combination of temperature and treatment
time, found that the aging temperature at 350oC and the aging
time from 1.5h-2h alloy for highest hardness.
IV. CONCLUSIONS
From the results of the analysis above can be concluded
about the organization and mechanical alloy change as
follows: At the beginning of the increase in the body
corresponds to the Spinodal spinning phase. The main
strengthening mechanism of the alloy is the Spinodal spinning
mechanism. When the temperature is too high or the time is
too long, the new phase is created as the hardening decreases.
Perform aging at 350 – 450oC for about 2 hours, receiving a
consistency consisting of a high hardness substrate, intermixed
with soft γ phase, in accordance with the requirements of the
heavy load-bearing of the engines.
REFERENCES [1] M. K. Pham, D. N. Nguyen, and A. T. Hoang, “Influence of Vanadium
Content on the Microstructure and Mechanical Properties of High-
Manganese Steel,” Int. J. Mech. Mechatronics Eng., vol. 18, no. 2, pp.
141–147, 2018. [2] A. T. Hoang, L. H. Nguyen, and D. N. Nguyen, “A Study of Mechanical
Properties and Conductivity Capability of CU-9NI-3SN ALLOY,” Int. J.
Appl. Eng. Res., vol. 13, no. 7, pp. 5120–5126, 2018. [3] X. D. Pham, A. T. Hoang, D. N. Nguyen, and V. V Le, “Effect of
Factors on the Hydrogen Composition in the Carburizing Process,” Int.
J. Appl. Eng. Res., vol. 12, no. 19, pp. 8238–8244, 2017. [4] R. T. Kiepura and B. R. Sanders, ASM Handbook: Metallography and
Microstructures. ASM International, 1985.
[5] K. Imai, “Bearing material for an internal combustion engine and compressor.” Google Patents, 12-Mar-1991.
[6] X. Liu, M. Q. Zeng, Y. Ma, and M. Zhu, “Promoting the high load-
carrying capability of Al–20 wt% Sn bearing alloys through creating nanocomposite structure by mechanical alloying,” Wear, vol. 294, pp.
387–394, 2012.
[7] H. Imazu and Y. Kojima, “Physical properties and combustion characteristics of emulsion fuels of water/diesel fuel and water/diesel
fuel/vegetable oil prepared by ultrasonication,” J. Japan Pet. Inst., vol.
56, no. 1, pp. 52–57, 2013. [8] M. T. Miglin, J. P. Hirth, A. R. Rosenfield, and W. A. T. Clark,
“Microstructure of a quenched and tempered Cu-bearing high-strength
low-alloy steel,” Metall. Trans. A, vol. 17, no. 5, pp. 791–798, 1986. [9] K. V Shankar and R. Sellamuthu, “An investigation on the effect of
nickel content on the wear behaviour and mechanical properties of
spinodal bronze alloy cast in metal mould,” Int. J. Mater. Eng. Innov., vol. 7, no. 2, pp. 89–103, 2016.
[10] S. Ilangovan and R. Sellamuthu, “Effects of tin on hardness, wear rate
and coefficient of friction of cast Cu-Ni-Sn alloys,” J. Eng. Sci. Technol., vol. 8, no. 1, pp. 44–54, 2013.
[11] J. Caris, D. Li, J. J. Stephens Jr, and J. J. Lewandowski, “Microstructural
effects on tension behavior of Cu–15Ni–8Sn sheet,” Mater. Sci. Eng. A, vol. 527, no. 3, pp. 769–781, 2010.
[12] S.-Z. Zhang, B.-H. Jiang, and W.-J. Ding, “Wear of Cu–15Ni–8Sn spinodal alloy,” Wear, vol. 264, no. 3–4, pp. 199–203, 2008.
[13] W. R. Cribb, “Copper spinodal alloys for aerospace,” Adv. Mater.
Process, vol. 6, p. 44, 2006. [14] F. Findik, “Improvements in spinodal alloys from past to present,”
Mater. Des., vol. 42, pp. 131–146, 2012.
[15] K. V Shankar and R. Sellamuthu, “Determination on the Effect of Tin Content on Microstructure, Hardness, Optimum Aging Temperature and
Aging Time for Spinodal Bronze Alloys Cast in Metal Mold,” Int. J.
Met., vol. 11, no. 2, pp. 189–194, 2017. [16] B. Alili, D. Bradai, and P. Zieba, “On the discontinuous precipitation
reaction and solute redistribution in a Cu-15% Ni-8% Sn alloy,” Mater.
Charact., vol. 59, no. 10, pp. 1526–1530, 2008. [17] W. Raymond, F. Cribb, M. J. Gedeon, and F. C. Grensing, “Copper-
Nickel-Tin Spinodal Alloys,” Adv. Mater. Process., p. 20, 2013.
[18] Z. Hui, H. Yizhu, Y. Xiaomin, and P. Ye, “Microstructure and age characterization of Cu–15Ni–8Sn alloy coatings by laser cladding,”
Appl. Surf. Sci., vol. 256, no. 20, pp. 5837–5842, 2010.
[19] J.-C. Zhao and M. R. Notis, “Spinodal decomposition, ordering transformation, and discontinuous precipitation in a Cu–15Ni–8Sn
alloy,” Acta Mater., vol. 46, no. 12, pp. 4203–4218, 1998.
[20] M. Miki and Y. Ogino, “Precipitation in a Cu-20% Ni-8% Sn alloy and the phase diagram of the Cu–Ni rich Cu–Ni–Sn system,” Trans. Japan
Inst. Met., vol. 25, no. 9, pp. 593–602, 1984.
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