Alumel

Alumel is a trade name for a nickel-based alloy containing approximately 94% nickel, 2% aluminum, 2.5% manganese, and 0.5% silicon. It is primarily used as the negative leg (–) of Type K thermocouples. Thermocouples employing Alumel are commonly used for temperature measurement in a variety of industrial applications due to their relatively wide temperature range, stability, and affordability.

The specific chemical composition can vary slightly depending on the manufacturer. Alumel is valued for its thermoelectric properties, specifically its ability to generate a predictable voltage difference in response to temperature changes when paired with a positive leg material, typically Chromel. This voltage difference is then correlated to a specific temperature reading.

Alumel is resistant to oxidation, but its performance can be affected by reducing atmospheres or the presence of sulfur. Therefore, care should be taken in selecting thermocouples with Alumel elements for use in certain environments. Its melting point is approximately 1400°C (2552°F).