CRYSTAL MORPHOLOGY AND MECHANISMS OF GROWTH OF ALPHA-FE2O3 WHISKERS ON IRON
WESTINGHOUSE RESEARCH LABS PITTSBURGH PA
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Growths on pure iron at 400 degrees C to 500 degrees C in dry oxygen were studied. Selected area electron diffraction patterns of individual whiskers as well as electron diffraction texture patterns of oxidized surfaces showed the whisker axis to be -1-120. The axial rotation indicated by the pattern is that resulting from an axial twist. The axial twist provides evidence that the most simple oxide whiskers have a single axial screw dislocation with a 5.03 A Burgers vector. Arguments are presented for the view that growth of the whisker occurs by diffusion of iron atoms or ions through the dislocation and reaction with oxygen at the tip.