Electrical-resistance alloys of copper, manganese, and aluminum

An investigation has been made of the electrical properties of alloys containing from 4 to 15 percent of manganese and from 0 to 10 percent of aluminum, the remainder being copper. An alloy containing 85 percent of copper, 9.5 percent of manganese, and 5.5 percent of aluminum has properties very similar to those of manganin. Its thermoelectric power against copper is much smaller than that of manganin and this thermoelectric power may be brought to zero by the addition of a very small amount of iron. Resistance coils constructed from these alloys, with or without added iron, have been very stable in resistance. By properly baking, their temperature coefficients of resistance at 25 C may be made as nearly zero as is desired, and this coefficient changes less with temperature than does that of manganin .