e妊'ect of nickel on characteristics of bismuth bronze castings

* *
Research Article ].]FS Vol. 81 No 4 (2009) pp.170~176
E'ectof Nickel on Characteristics of Bismuth Bronze Castings
Masaaki Yamamoto* and Yoshimasa Hirai*
In this study effects of Ni on fluidity formation of shrinkage mechanical properties and machinability were studied for bismuth lead-free copper alloy castings. The fluidity of Cu1.5Ni-4.5Sn-6.5Zr0.03Palloy was comparable to that
of CAC406. The amount of shrinkage cavity reduced at an Ni content of 1.5mass% or higher. Mechanical properties
tended to decrease with increasing content of Bi and at a Bi content of 2.0mass% or lower the tensile strength exceeded 195MPa and elongation was over 15%. The machinability coefficient was 80 to 90% of CAC406 which enables good machining of the castings. Addition of Ni effectively reduces the Sn concentration in the liquid ahead of the solid-liquid
interface during solidification to prevent segregation of Sn and to form compounds together with Sn and P between
dendrite arms. Formation of compounds reduces shrinkage cavities and also serves as chip breakers during machining thereby improving machinabili
Keywords : lead free copper alloy nickel bismuth castability shrinkage mechanical properties machinability
1.
. Pb
2.2

.
2.4
.

. Fig.4
1367K 1424K 1446K
Fig. 3 Observation of fluidity test specimens.
800
11OCu4.6Sn-6.6Zn-1.5Ni-1.6BO.03P1
400 300 0
flow length.
(0-3.3) Bi-0.03P.
1.5mass%Ni
aoH

u
n
u
h
v

u
n
u
w o h u p o n u k u n v
q
strength and elongation with Cu6Zn-2.5Ni-O.5Bi-xSn
alloy.
(c) 5mass%Sn content

o-

U
h
u
h
u
o

strength and elongation with Cu5Sn-6Zn-O.5BixNi
allo)ι
alloy.
4 2
40 '#.
0 o 0
n
u
n
u
n
u
aaτ
“
Y
0.050 0.100 P mass%
xP alloy.
strength and elongation with Cu-5Sn6Zn2.5Ni-xBi
alloy.
0
θ
300
n
u
n
u
n
u
A
U
A
U
machinability coefficient with Cu(2.55)Sn6Zn2.5Ni-
xBi alloy.
strength with Cu4.5Sn-1.6Ni7Zn-1.5Bi0.04Palloy.
40 35 15 180
87 4mass%Bi
Fig.
. 2_5mass%
50Fig.11
BiFig.12.
Bi. BiPb
α
(c) Cu-5Sn-7Zn-2.5Ni-(00.51.32.02.9) Bi-0.03P
Fig. 13 Comparison of chip-shape of CuNi(2.55.0)SnZnxBialloy and CAC406C.
(d) 2.0mass%Ni content
(c) 1.5mass%Ni∞ntent
Fig. 14 Microstructure of Cu5.0Sn6ZnxNiO.5BiO.03Pallo)
175
.Ni
'5mass%SnCu5.1Sn6.1Zn-2.5Ni3.3Bi-O.02P.
Fig.15 (a) (b). 2.5mass%Sn
2.5mass%Sn ∞ntent" '" (b) 5.0mass%Sn content
Fig. 15 Result of EPMA analysis.
NiSn?. Bi.
Fig. 16 (a) (b)Cu-(2.5 5) Sn-7Zn(l ~4) NiO.5Bi
O.03PNi Ni.
Ni-Sn~Ni-P
1.0
~ 0.6 b
0.0
0
0
ratio of Ni compound.
Ni-Sn
2.5Ni1~2Bi- 0.05P .

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79(2007) 380
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147 (2005)38