ELECTRON MICROSCOPE STUDIES OF THE SURFACE STRUCTURE OF WHISKERS GROWN FROM IRON CHLORIDE,

In continuing the investigation of iron whiskers by electron microscopy, additional evidence was obtained concerning the mechanism of filamentary growth as it is reflected in surface structure. During the past year whisker specimens were produced under new types of growth conditions with ultra-pure ferrous chloride containing small amounts of cobaltous chloride at 700 C. Although individual whiskers within each specimen boat may vary somewhat, their surface topography appears to follow definite patterns. In most specimens, regardless of growth conditions, these typical patterns show variation in surface structure from the base to the tip areas. Detail in surface contours appears to be more uniform in whiskers which develop well-formed tips. When whiskers grown with the addition of cobaltous chloride could be broken, their fractured crosssection surfaces exhibited a shell and core structure similar to that found in whiskers which were previously studied in this program. Author