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Effects of Titanium in Alnico 8-Type Magnet Alloys

1970; Japan Institute of Metals and Materials; Volume: 11; Issue: 4 Linguagem: Inglês

10.2320/matertrans1960.11.268

2432-4701

Yoshiro Iwama, Matsumi Inagaki, Toshinobu Miyamoto,

Metallic Glasses and Amorphous Alloys

Alnico 8-type magnet alloys containing more than 5% Ti have been well-known to have very high coercive forces, particularly when the isothermal field treatment is applied. As a primary approach in this research to explore its cause, the transformations, microstructures and magnet characteristics were investigated in a series of Alnico 8-type alloys with various titanium contents. The critical temperatures of the transformations including magnetic transition were determined as a function of titanium content. It may be reasonably concluded that the mechanism of magnetic hardening in these alloys is similar to that in Alnico 5-type alloys containing no titanium.It was shown that when the alloys were subjected to isothermal field treatment, the coercive fore obtained depended largely upon the temperature of the treatment, and slightly upon the treating time. In each of the specimens, the optimum temperature of the treatment was found to exist about 50°C below the critical temperature of the two-phase separation reaction and to raise as the titanium content was increased. In addition, the magnetic anisotropy induced by the heat treatments in a magnetic field seems rather to decrease in magnitude with increasing titanium content. Furthermore, the electron microscopic observation has revealed that the precipitate particles developed by the optimal treatment are likely to increase in both size and dimension ratio with increasing titanium content.