The variation of power loss and domain wall spacing with applied stress in wide amorphous ribbon material

The power loss of wide, 1.3 cm, ribbons of commercially produced Metglas 2826 (Fe40Ni40P14B6) have been measured under sinusoidal flux conditions. These measurements have been performed on samples in the as-cast unpolished, annealed unpolished, as-cast polished and annealed polished condition over a frequency range from 20 to 1000 Hz at flux densities up to 0.75 T. The variation of power loss with tensile stress applied in the direction of the ribbon length over the range 0 to 25 MPa (0 to 3600 psi) has been determined. The variation of domain configuration with tensile stress for the annealed polished samples has been observed by the Kerr magneto-optic effect technique. The static hysteresis loss of the ribbons has been reduced by the application of the tensile stress but at higher frequencies the stressed samples exhibit a higher power loss. The total power loss has been divided into the major constituent losses and the high excess eddy current loss is attributed to the observed high domain wall spacing to thickness ratio. The effect of polishing the ribbons in order to observe the domains is to introduce a complex stress which increases the power loss. The power loss of the annealed samples has not been reduced by the application of the tensile stress.