Constantan is a copper–nickel alloy composed typically of 55% copper and 45% nickel, prized for its nearly constant electrical resistance over a wide temperature range. This unique property makes it indispensable in precision resistors, thermocouples, and other electrical components requiring stability under varying environmental conditions. Its balanced composition delivers a combination of moderate resistivity, mechanical strength, and superior corrosion resistance.
Material Overview
Constantan’s resistivity at 20 °C is approximately 49 × 10−8 Ω·m, with a temperature coefficient of resistance near zero, ensuring reliable performance even in dynamic temperature environments. The alloy crystallizes in a face-centered cubic (FCC) structure, offering high ductility and excellent workability. Research by Chadjivasiliou et al. (1980) revealed a resistivity minimum at ~673 K due to short-range order cluster formation, confirming its thermal stability. Modern investigations (Guo et al., 2021) have refined Cu–Ni alloy design to reduce thermal conductivity while maintaining strength through hierarchical architectures. Moreover, Muta et al. (2003) demonstrated that dispersing SiO2 or Al2O3 particles into a Cu–Ni matrix slightly enhances the Seebeck coefficient, underlining Constantan’s thermoelectric versatility.
Applications and Advantages
Constantan’s near-zero temperature coefficient of resistance and corrosion resilience make it ideal for precision measurement and control systems. It is extensively used as the negative leg in type J (Fe–Constantan) and type T (Cu–Constantan) thermocouples, providing stable readings across temperature extremes. The alloy’s predictable resistance also supports the manufacture of strain gauges, resistive sensors, and precision shunt resistors. Recent thin-film studies (Hur et al., 2005) highlight that Constantan films on AlN substrates achieve TCR values as low as 7 ppm °C, ensuring superior performance in microelectronic resistor networks. These properties, coupled with its excellent formability, make Constantan indispensable in both industrial and cryogenic applications.
Goodfellow Availability
Goodfellow provides Constantan (Cu55/Ni45) alloy wire in research-grade purity and customizable dimensions. All products are manufactured to high tolerances, ensuring excellent surface finish and uniform resistivity. Custom compositions and dimensions are available on request to support experimental or prototype needs in thermoelectric, sensing, or resistive applications.
Explore Constantan - Resistance Alloy (Cu55/Ni45) - Wire - Material Information and other advanced materials in Goodfellow’s online catalogue: Goodfellow product finder.
References
- Chadjivasiliou, S. C., Tsoukalas, J. A., Papadimitraki-Chlichlia, H., Antonopoulos, J. G., Karakostas, T., & Economou, N. A. (1980). On the high temperature electrical resistivity behaviour of Cu55–Ni45 alloy. Materials Research Bulletin, 15(11), 1559–1564.
- Muta, H., Kurosaki, K., Uno, M., & Yamanaka, S. (2003). Thermoelectric properties of constantan/spherical SiO? and Al2O3 particles composite. Journal of Alloys and Compounds, 356–357, 517–520.
- Hur, S.-G., Kim, D.-J., Kang, B.-D., & Yoon, S.-G. (2005). The structural and electrical properties of CuNi thin-film resistors grown on AlN substrates for ?-type attenuator application. Journal of the Electrochemical Society, 152(6), G453–G458.
- Guo, K., Zhang, J., Zhang, Y., Liu, L., Yuan, S., Jiang, Y., Luo, J., & Zhao, J.-T. (2021). Minimizing thermal conductivity for boosting thermoelectric properties of Cu–Ni-based alloys through all-scale hierarchical architectures. ACS Applied Energy Materials, 4(8), 8282–8291.
- Cao, X., Li, J., Zhang, J., Li, M., Kang, H., Guo, E., Chen, Z., Chen, R., Wang, J., & Wang, T. (2023). Enhancing the thermoelectric and mechanical properties of CuNiMn alloys by introducing Si impurity atoms and twins. ACS Applied Electronic Materials, 5(9), 4118–4129.