The Magnetic Properties of Some Iron Alloys Melted in Vacuo

In a paper presented before the Urbana Section, April 16, 1914, the author described results obtained from tests made on pure iron melted in vacuo, to obtain data as to its magnetic and allied properties. The present paper describes further experiments on various alloys of the electrolytic iron melted in vacuo with other elements. The author deals briefly with the iron-boron and iron-carbon alloys, and presents results obtained with the iron-cobalt alloy Fe2Co, but gives in greater detail the data in regard to iron-silicon alloys, from which the most remarkable results were obtained. The two best alloys were obtained with about 0.15 per cent and 3.40 per cent silicon, after annealing at 1100 deg. cent. The values of maximum permeability for both of these alloys are above 50,000, and the values of hysteresis loss for Bmax = 10,000 and 15,000 are about 300 and 1000 ergs per cu. cm. per cycle, respectively. This hysteresis loss is 1/8 and 1/3 of the corresponding loss for commercial silicon steel. While both alloys have similar magnetic properties, the 3.40 per cent silicon alloy has a specific electrical resistance nearly five times that of the 0.15 per cent alloy, making it particularly desirable for use in electromagnetic machinery in places where a low eddy-current loss is a requirement, in addition to high permeability and low hysteresis loss.