Other Naturally Hard Copper Alloys

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

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)

References

References