1994 Volume 58 Issue 4 Pages 455-460
The effects of the addition of Cr and Ti on wear and soft magnetic properties has been investigated for Fe-Al-Si alloys in order to improve the wear resistance of heads for VTRs. We find that the head wear rate increases greatly with increasing relative humidity, and varies depending on the tape properties. The surface hardness of magnetic tapes increases with increasing relative humidity and is high in the case of highly abrasive tapes. Addition of Ti and Cr increases the hardness and the corrosion resistance of the Fe-Al-Si alloy and reduces the wear rate, especially for the highly abrasive tapes, and the high relative humidity. A minimum coercivity and a maximum permeability have been obtained in the 7.5∼8 mass%Si and 7.5∼9.5 mass%Al Sendust alloy with 3 mass%Cr and 1 mass%Ti. This optimum composition coincides with that in which the magnetocrystalline anisotropy constant, K1, and the magnetostriction constant, λs, is close to zero. The alloy with 3 mass%Cr and 1 mass%Ti and with optimum Si and Al concentrations shows lower coercivity, higher permeability and higher electrical resistivity, ρ, than the conventional Sendust alloy. The heads for broadcast VTRs using this alloy are 20∼30% higher in output than the conventional head.
