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Nicrosil is a nickel alloy containing about 14.4% chromium, 1.4% silicon, and (in some sources) 0.1% magnesium.[1]
Nicrosil is used as the positive leg of type N thermocouples. In this application another nickel alloy, Nisil, is used as the negative leg.[2] The Nicrosil alloy in this case does not contain magnesium.[2]