Research Laboratories, Kawasaki Steel Corp., 1, Kawasaki-cho, Chuo-ku, Chiba 260
In order to clarify the mechanism responsible for the ultra-low iron loss of TiN-coated grain oriented silicon steel sheet, the structure of TiN films and steel sheet in the vicinity of the near-surface of the (011) single crystal of silicon steel was observed by transmission electron microscope (TEM). The sample for observation of TEM was taken initially by mechanical processing from a marked domain-refined area of the TiN-coated silicon steel sheet, and finally thinned by using the focused ion beam (FIB) technique.
Diffraction patterns of TiN films and silicon steel sheet were satisfactory, showing (110)TiN//(100)Si-steel, [1 1]TiN//Si-steel. The degree of coherency between [1 1]TiN and Si-steel showed a good value of 4.5%. An intermixed layer of TiN and silicon steel about 10 nm in width with fine transverse fringes was also observed.
It should be emphasized that the ultra-low iron loss in the TiN-coated silicon steel sheet obtained by inducing radical domain refinement can be achieved by good coherency between the TiN films and single crystal of silicon steel with (011), namely, the Goss orientation, in which the difference of the thermal expansion coefficients of the ceramic TiN films and silicon steel sheet, after cooling from 973 K plasma coating to room temperature, strongly tensions the near-surface of the TiN-coated silicon steel sheet to the Si-steel direction (elastic strain along one axis).
(Received April 1, 1996)
grain oriented silicon steel, TiN film, domain refinement, coherency, (1
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