Magnetic properties and corrosion resistance of Fe-based sputtered films

The effects of elements added to Fe-based sputtered films are investigated to obtain magnetic thin films with a high-saturation magnetic flux density, Bs, a zero magnetostriction constant, λs, and high corrosion resistance. The Fe films, sputtered at argon pressures below 10 mTorr, have the same Bs as bulk samples. They also show high corrosion resistance. Although the λs of Fe film has a large absolute value, zero-magnetostriction films are obtained by the addition of 1 to 5at% Si, Cr, Mo, Ni, Ru or Rh. Samples containing Ni or Rh maintain a high Bs, of about 21 kG. However, the addition of Si, Mo and Cr cause a marked deterioration in corrosion resistance, while samples containing Ni, Ru or Rh show high corrosion resistance. The anodic polarization curves show that films with high corrosion resistance have high pitting potentials. This result suggests that the pitting is dominant in the corrosion of Fe-based films.