. The Bell System technical journal . ining 25 percent nickel and 10 per cent aluminum, after cjuenching from 1200° C. in oil. In thiscondition the alloy has its optnnum permanent magnet quality. Mag. 125 X. If on-Cobalt-Molybdenum and Iron-Cobalt-Tungsten Alloys The age hardening characteristics of alloys in these systems wereestablished some years ago by Sykes, who developed the alloys fortools. Later, Seljesater and Rogers ^^ reported that these alloys possesspciTnanent magnet characteristics. A detailed report on the magnetproperties has been made by Koster. Of the two systems, it appears
. The Bell System technical journal . ining 25 percent nickel and 10 per cent aluminum, after cjuenching from 1200° C. in oil. In thiscondition the alloy has its optnnum permanent magnet quality. Mag. 125 X. If on-Cobalt-Molybdenum and Iron-Cobalt-Tungsten Alloys The age hardening characteristics of alloys in these systems wereestablished some years ago by Sykes, who developed the alloys fortools. Later, Seljesater and Rogers ^^ reported that these alloys possesspciTnanent magnet characteristics. A detailed report on the magnetproperties has been made by Koster. Of the two systems, it appears MAGNETIC MATERIALS IN RELATION TO STRUCTURE 35 that appreciably higher coercive forces are available in the one con-sisting of iron, cobalt and molybdenum. In Fig. 17 are shown thecombinations of residual induction and coercive force obtained byKoster in the latter system with variations in molybdenum and cobaltcontent. Coercive forces of over 200 oersteds, associated with residualinductions of approximately 10,000 gauss, are Fig. 16—Structure of the same alloy shown in Fig. 15 after a subse([uent agingtreatment of 24 hours at 1000° C. This treatment has resulted in the precipitationof a large amount of the second phase. Mag. 125 X. The desirable properties of this class of materials are developed by adouble heat treatment which consists of a quench from a high tempera-ture followed by aging at a lower temperature. The alloys are precipi-tation hardening in the same manner as the non-ferrous copper-beryllium alloys or lead-calcium cable sheath alloys. The heat treat-ment is illustrated in Fig. 18, which shows the effect of aging on the 36 BELL SYSTEM TECHNICAL JOURNAL properties of an alloy containing 15 per cent cobalt and 18 per centtungsten reproduced from Rosters published data. The alloy wasinitially quenched from a temperature of 1300° C, and subsequently 300 19^ Mo ^ ^ ^ _^ -— ^ 16^ Mo 100 -- -^ 13^ Mo —^ -^ 10^ Mo 1rv Z 11,000 9000 7000
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