INFLUENCES OF SUBSTRATES AND ANNEALING AT MOSPHERE ON CORROSION-RESISTANCE OF AL DOPED FE-TA-C MAGNETIC THIN-FILMS

Influences of substrate materials and oxygen content in an annealing a tmosphere on the corrosion resistance of A-doped Fe-Ta-C, magnetic thi n films were studied by electrochemical methods. The reaction speed of pitting corrosion of Al doped Fe-Ta-C magnetic thin films prepared on a single crystalline Mn-Zn ferrite substrate was faster than that of the film prepared on a glass substrate. The high corrosion rate was as sociated with degradiation of the Fe (110) orientation, when the magne tic thin film was prepared on the ferrite substrate. When the A-doped Fe-Ta-C films were annealed in an atmosphere containing oxygen, the pi tting potential shifted to less noble potentials. The corrosion mechan ism was studied by AES and ESCA. When the Al-doped Fe-Ta-C magnetic th in films were exposed to oxygen in the annealing atmosphere, Al in the alloys was preferentially oxidized and its concentration was reduced. As a result, the magnetic film became weak against pitting corrosion.