Other Naturally Hard Copper Alloys

5.1.5.1 Copper-Nickel Alloys

Copper and nickel are in their solid and liquid phase completely soluble in each other Figure 1 (Fig. 5.21). Because of their very low electrical conductivity they are mainly used as resistance alloys Figure 2 (Fig. 5.22). The work hardening and softening behavior of CuNi alloys and CuNi9Sn2 are shown in (Figs. 3 – 7) Figs. 5.23 – 5.27. Coppernickel alloys exhibit high corrosion resistance, good weldabilty, and the suitability for cladding to other materials. Because of these and their other properties (Tables 5.15 and 5.16) 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).

5.1.5.2 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 Fig. 5.21: Phase diagram of copper-nickel for the range of 0 – 50 wt% nickel

Figure 2 Fig. 5.22: 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 5.15: Physical Properties of Selected Copper-Nickel Alloys

Material Designation EN UNS	Composition [wt%]	Density [g/cm3]	Electrical Conductivity [MS/m] [% IACS]		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]
CuAg2 not standardized	Ag 2 Cu Rest	9.0	49	85	2.0	330	17.5	123	ca. 330	1050 - 1075
CuAg2Cd1,5 not standardized	Ag 2 Cd1,5 Cu Rest	9.0	43	74	2.3	260	17.8	121	ca. 350	970 - 1055
CuAg6 not standardized	Ag 6 Cu Rest	9.2	38	66	2.4	270	17.5	120		960 - 1050

Table 5.16: 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]
CuAg2	R 280 R 380 R 450 R 550	280 - 380 380 - 460 450 - 570 ≥ 550	≤ 180 ≥ 300 ≥ 420 ≥ 500	30 6 3 1	50 - 110 100 - 140 130 - 165 ≥ 160	0 x t 0 x t 1 x t	0 x t 0 x t 1 x t	400	190
CuAg2Cd1,5	R 300 R 380 R 480 R 600	300 - 380 380 - 490 480 - 620 ≥ 600	≤ 190 ≥ 310 ≥ 440 ≥ 550	30 8 3 1	55 - 110 100 - 145 130 - 170 ≥ 160	0 x t 0 x t 1 x t	0 x t 0 x t 1 x t	440	220
CuAg6	R 320 R 400 R 500 R 650	320 - 400 400 - 510 500 - 660 ≥ 650	≤ 210 ≥ 330 ≥ 460 ≥ 610	30 6 3 1	70 - 120 110 - 150 145 - 175 ≥ 175	0 x t 0 x t 1 x t	0 x t 0 x t 1 x t	460	230

¹⁾ t: Strip thickness max. 0.5 mm

Figure 3 Fig. 5.23: Strain hardening of copper-nickel alloys as a function of nickel content

Figure 4 Fig. 5.24: Strain hardening of CuNi25 by cold working

Figure 5 Fig. 5.25: Softening of CuNi25 after 1 hr annealing after 50% cold working

Figure 6 Fig. 5.26: Strain hardening of CuNi9Sn2 by cold working (Wieland)

Figure 7 Fig. 5.27: 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