Title :
Increase in thermal stability of soft magnetic Fe-C/Ni-Fe multilayers with addition of Ta
Author :
Kobayashi, Toshio ; Nakatani, Ryoichi ; Nakamura, Hitoshi
Author_Institution :
Hitachi Ltd., Tokyo, Japan
fDate :
9/1/1990 12:00:00 AM
Abstract :
The thermal stability of Fe-C/Ni-Fe multilayers was investigated by adding Ta, which combines with C to form high-melting-point Ta carbides. It was found that the temperature at which the relative permeability of the Fe-C-Ta/Ni-Fe multilayers started to decrease rose with the addition of Ta. This temperature rose to 620°C at a Ta concentration of 1.6 at.%. Improvement in the thermal stability occurred when Ta and C coexisted and Ta carbides were formed in a film. The existence of the Ta carbides is thought to restrain crystallite growth. When heat treatment was conducted at 700°C, α-Fe(C) partially changed into γ-Fe(C), which decreased the saturation magnetic flux density. The addition of Ta lessened this reduction
Keywords :
crystallites; heat treatment; iron alloys; iron compounds; magnetic flux; magnetic permeability; magnetic thin films; nickel alloys; tantalum compounds; α-Fe(C); γ-Fe(C); 620 degC; 700 degC; FeCTa-NiFe; Ta concentration; crystallite growth; heat treatment; high-melting-point Ta carbides; relative permeability; saturation magnetic flux density; soft magnetic multilayers; thermal stability; Crystallization; Heat treatment; Magnetic films; Magnetic flux; Magnetic multilayers; Permeability; Saturation magnetization; Soft magnetic materials; Temperature; Thermal stability;
Journal_Title :
Magnetics, IEEE Transactions on
