Abstract
Fourier analysis was applied to characterize solidification structures of metals. Optical micrographs of dendritic structures of some cast aluminum-copper alloys were transformed into a series of digital signals and analyzed by computer. Results of analysis were expressed as power spectrum, i.e. frequency distribution of wave length and direction. The peaks of the spectrum, i.e. length and direction of the most frequently observed wave, coincide with the spacing and direction of dendrite measured by the conventional method. Since the present method is fully automatic, it is expected to be more reproducible in characterizing solidification structures than when using the conventional concept of dendrite arm spacing, which is often dependent on personal judgement and skill. Besides the information of the major wave element, information on minor wave elements is also obtained by the present method and can be utilized if necessary.
