Kopel - CuNi44Mn - Curethal® wire

International Equivalent

Mark Analogue W. Nr. Aisi Uns En Order
MNMts43-0.5 CuNi44Mn1 Delivery from the stock, in stock

The more categorical the point of view, the less we know about the subject. Karel Capek.


Kopel is a thermoelectric copper-nickel alloy containing 43-44% nickel (Ni), 2-3% iron (Fe), 0.5% manganese (Mn). A percentage of the remainder is copper (Cu). In terms of its merits, this alloy is close to another copper-nickel alloy - constantan.

Advantages of

High corrosion and heat resistance, can withstand heat up to 800 °C without loss of basic properties. Possesses the maximum thermal EMF in pair with copper, chromel and iron. The temperature coefficient of electrical resistance is minimal. This property is unique to this alloy.

Physical properties

The density is 8.9 g/cm³, the temperature coefficient of linear expansion is 14-10-6 °C-1, the specific electrical resistance is 0.5 μOh-mm2/m. The thermal EMF at 100 °C is 6.95 volts and increases to 49.0 volts at 600 °C. The melting point = 1290 °C, the alloy can be hot worked at t° of 1150 °C, and the annealing of the alloy is done at 800-850 °C.


The main area of application is pyrometry, so the main type of rolled steel is wire, less often ribbon and round. Thermocouples with maximum thermal EMF are used to obtain accurate data when measuring low temperatures. Copper, iron, chromel are used for positive electrode, and alumel, constantan, copel are used for negative electrode. The leading thermocouple in terms of thermo-EMF is chromel-copel (TCK). It is used for t° up to 800 °C, followed by copper-copel and iron-copel (up to 760 °C). Kopel is also used to make compensation wires. For these purposes, wire of different diameters is made, but with strict specifications, according to GOST 3044-84. The cost of wire depends on the diameter of the product, the smaller the diameter, the relatively higher the price.

The chemical composition of kopel MNMts 43-0,5 in % of metals

Ni+Co Fe C Si Mn Cu Impurities
42.5 - 44 ≤ 0.15 ≤ 0.1 ≤ 0.1 0.1 - 1 54.4 - 57.4 total 0.6


The most common grade of kopel is MNMz 43-0.5. It is supplied in wire form (diameter 0.10 - 12.0 mm), as a circle (Ø 12.0 - 100.0 mm), and as a strip with a thickness of 0.1-5.0 mm and a width of 3-600 mm.

Physical properties of kopel alloy MNMC 43-0.5 at 20 °C

Hardness, alloy soft HB 10 -1 Hardness, alloy hard HB 10 -1 Melting temperature, °C: Hot work temperature, °C: Annealing temperature, °C:
= 85 - 90 MPa = 185 MPa 1290 1000 - 1150 800 - 850