Alumel


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alumel

[′al·yü·mel]
(metallurgy)
An alloy containing 94% nickel, 2% aluminum, 3% chromium, and 1% silicon; used to form the chromel-alumel thermocouple.

Alumel

 

an alloy used in pyrometry as the negative ther-moelectrode of the Chromel-Alumel thermocouple and also as a compensation conductor.

The chemical composition of Alumel is 1.8–2.5 percent aluminum, 0.85–2.0 percent silicon, and 1.8–2.2 percent manganese; the remainder is nickel and cobalt. The cobalt is present as an impurity of nickel and, to ensure the required value of the thermoelectric force, its content must be within the range of 0.6–1.0 percent. Thermocouples with Alumel are used in measuring temperatures up to 1000°C. On prolonged exposure at above 1000°C, a change in thermoelectric force becomes very noticeable. Alumel alloys have been developed and used which contain 0.06 -0.1 percent zirconium or 0.06 percent zirconium plus 0.005–0.03 percent boron and other metals. Such alloying of Alumel substantially increases its ductility (at temperatures of 600–1100°C) and durable strength (at temperatures of 700 -900°C), as well as improving the stability of its thermoelectric force at temperatures up to 1250 -1300°C.

REFERENCES

Berkovskii, I. Ia., and A. G. Kolokolova. Nikelevye splavy.
Moscow-Leningrad, 1941. Popov, M. M. Termometriia i kalorimetriia, 2nd ed. Moscow, 1954.
Smiriagin, A. P. Promyshlennye tsvetnye metally i splavy, 2nd ed. Moscow, 1956.
“Issledovanie splavov dlia termopar.” Trudy instituta “Giprots-vetmetobrabotki,” 1964, vol. 22; 1967, vol. 25.

A. L. SHPITSBERG

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