Other Naturally Hard Copper Alloys

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Copper-Nickel Alloys

Copper and nickel are in their solid and liquid phase completely soluble in each other Figure 1. Because of their very low electrical conductivity they are mainly used as resistance alloys Figure 2. The work hardening and softening behavior of CuNi alloys and CuNi9Sn2 are shown in (Figs. 3 – 7). Coppernickel alloys exhibit high corrosion resistance, good weldabilty, and the suitability for cladding to other materials. Because of these and their other properties Table 1 and Table 2 they are, with and without additives of iron or manganese, widely used as good weldable backing layers on weld buttons and weld profiles (weld tapes).

Copper-Nickel-Tin Alloys

Copper-Nickel- multi component alloys with 9 wt% Ni and 2 wt% Sn are used mainly as connector materials because of their suitable mechanical properties, their excellent relaxation behavior, and their high corrosion resistance. Other advantages include their high temperature stability and the good solderability even after longer storage. They are also used as base materials for clad profiles and tapes.

Figure 1 Phase diagram of copper-nickel for the range of 0 – 50 wt% nickel

Figure 2 Electrical conductivity of copper-nickel alloys as a function of nickel content

Figure 1: Phase diagram of copper-nickel for the range of 0 – 50 wt% nickel
Figure 2: Electrical conductivity of copper-nickel alloys as a function of nickel content


Table 1: Physical Properties of Selected Copper-Nickel Alloys
Material
Designation
EN UNS
Composition
[wt%]
Density
[g/cm3]
Electrical
Conductivity
Electrical
Resistivity
[μΩ·cm]
Thermal
Conductivity
[W/(m·K)]
Coeff. of Linear
Thermal
Expansion
[10-6/K]
Modulus of
Elasticity
[GPa]
Softening Temperature
(approx. 10% loss in
strength)
[°C]
Melting
Temp Range
[°C]
[MS/m] [% IACS]
CuNi25
CW350H
C71300
Ni 24 - 26
Mn 0.5
Zn 0.5
Fe 0.3
Cu Rest
8.94 3.0 5.2 33.3 29 15.5 147 ca. 500 1150 - 1210
CuNi9Sn2
CW351H
C72500
Ni 8.5 - 10.5
Sn 1.8 - 2.8
Mn 0.3
Fe 0.3
Cu Rest
8.89 6.4 11 15.6 50 16.5 140 ca. 480 1060 - 1120
CuNi10Fe1Mn
CW352H
C70600
Ni 9.0 - 11.0
Fe 1.0 - 2.0
Mn 0.5 - 1.0
Zn 0.5
Cu Rest
8.92 5.6 9 17.9 50 16.5 134
CuNi30Mn1Fe
CW354H
C71500
Ni 30 - 32
Mn 0.5 - 1.5
Fe 0.4 - 1.0
Zn 0.5
Cu Rest
8.93 2.6 4 38.5 29 15.5 152 1180 - 1240


Table 2: Mechanical Properties of Selected Copper-Nickel Alloys
Material Hardness
Condition
Tensile Strength Rm
[MPa]
0,2% Yield Strength
Rp02
[MPa]
Elongation
A50
[%]
Vickers
Hardness
HV
Bend Radius1)
perpendicular to
rolling direction
Bend Radius1)
parallel to
rolling direction
Spring Bending
Limit σFB
[MPa]
Spring Fatigue
Limit σBW
[MPa]
CuNi25 R 290 ≥ 290 100 30 70 - 100
CuNi9Sn2 R 340
R 380
R 450
R 500
R 560
340 - 410
380 - 470
450 - 530
500 - 580
560 - 650
≤ 250
≥ 200
≥ 370
≥ 450
≥ 520
20
8
4
2
75 - 110
100 - 150
140 - 170
160 - 190
180 - 210
0 x t
0 x t
0 x t
1 x t
0 x t
0 x t
0 x t
2 x t
520 250
CuNi10Fe1Mn R 300
R 320
≥ 300
≥ 320
≤ 100
≤ 200
20 70 - 120
≥ 100
CuNi30Mn1Fe R 350
R 410
350 - 420
≥ 410
≤ 120
≤ 300
35 80 - 120
≥ 110

1) t: Strip thickness max. 0.5 mm

Figure 3 Strain hardening of copper-nickel alloys as a function of nickel content

Figure 4 Strain hardening of CuNi25 by cold working

Figure 5 Softening of CuNi25 after 1 hr annealing after 50% cold working

Figure 6 Strain hardening of CuNi9Sn2 by cold working (Wieland)

Figure 7 Softening of CuNi9Sn2 after 1 hr annealing after 60% cold working (Wieland)

Strain hardening of copper-nickel alloys as a function of nickel content
Figure 4: Strain hardening of CuNi25 by cold working
Figure 5: Softening of CuNi25 after 1 hr annealing after 50% cold working
Figure 6: Strain hardening of CuNi9Sn2 by cold working (Wieland)
Figure 7: Softening of CuNi9Sn2 after 1 hr annealing after 60% cold working (Wieland)

References

References