Shôtaro Shimizu1 and Eigô Hashimoto1
1Technical Laboratory, Citizen Watch Co., Ltd., Tokyo
The behavior of atomic ordering and magnetic hardening in Pt-Pd-Fe alloys were studied with interest in permanent magnetic alloys. About fifty alloys were prepared by powder metallurgy in the composition range of 0 ∼ 60 at%Pt, 0 ∼ 50 at%Pd and 40 ∼ 65 at%Fe. After various heat treatments, the magnetic properties were measured and the crystal structure were studied by X-ray diffraction. The results are summarized as follows:
(1) In Pt-Pd-Fe alloys containing a sufficient amount of Pd, the ordering transformation can be intercepted by quenching from high temperatures. And these alloys show the magnetic hardening by the aging process after quenching. For the occurrence of this effect, the alloys containing 50, 55 and 60 at%Fe require to contain 20, 10 and 5 at%Pd respectively.
(2) Since the coercive force is lowered in itself by Pd addition, optimum magnetic properties are obtained in 35Pt-5Pd-60Fe alloy, as an example, Br=8300 G, Hc=2400 Oe, (BH)max=7.4 MG Oe are obtained.
(3) Comparing the processes of ordering and magnetic hardening in this alloy with that in the PtCo alloy, it appears that the magnetic hardening in the former takes place in a later stage of atomic ordering than in the latter.
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