Abstract
Following the discovery of new magnet alloy “Malcolloy” of high coercivity in the Co–Al system, the present authors have made a series of experiments on the effect of the addition of nickel, molybdenum, titanium and vanadium on properties of Co–Al alloys, and obtained the highest coercive forces of 1450∼1600 Oe. Further, they have found that the coercive force and the maximum energy product of Co–Al alloys are generally increased by the addition of chromium: An alloy composed of 82.11% Co, 14.12% Al and 3.77% Cr shows the coercive force of 1450 Oe, the residual magnetic flux density of 3150 G and the maximum energy product of 1.42×106 G·Oe when tempered at 550°C for 15 hrs after water-quenching from 1375°C. The highest maximum energy product among all the alloys studied is 2.40×106 G·Oe. Such high-coercivity alloys consist of many elongated particles of a ferromagnetic phase, about 300 in diameter, dispersed in the matrix of a nearly nonmagnetic β′ phase, from which it is apparent that their high coercivity is mainly due to the presence of the fine particles of a single magnetic domain.
