Abstract
We have performed condensation experiments of metallic iron in vacuum by evaporation of iron and its recondensation along a temperature gradient. Metallic iron powder was placed at bottom of alumina or mullite tube and evaporated in vacuum furnace at 1390oC. Iron gas was recondensed on an inner wall of alumina or mullite tube along a temperature gradient of vacuum furnace. Condensed iron was observed and analyzed by SEM/EDX. Although it was a metallic iron, various morphologies of condensed metallic iron were observed as a function of the condensation temperature. At the condensation temperature (from 1160oC to 1250oC), shapes of condensed iron were close cubic or like a rectangular parallelepiped. At the condensation temperature ranging from 1110oC to 1160oC, iron grains like a rectangular parallelepiped moreover grow like whisker. At the condensation temperature ranging from 700oC to 1100oC, it was large(~10um) irregular particle or small(~1um) particle. Metallic iron has bcc-structure blow 911oC and fcc-structure above 911oC. We want to discuss how this morphology change of metallic iron occurs by examining a relation between its morphology and its structure of crystals.
