Accession Number : ADA115098

Title :   Structural Characterization of Schladitz Whiskers.

Descriptive Note : Final technical rept. 1 Feb 76-28 Feb 82,

Corporate Author : VIRGINIA UNIV CHARLOTTESVILLE SCHOOL OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s) : Wilsdorf,H G F

PDF Url : ADA115098

Report Date : May 1982

Pagination or Media Count : 49

Abstract : Polycrystalline iron whiskers containing 1.5 w/o C and O.8% O have an extraordinary ultimate tensile strength between 6 and 8 GPa. Their microstructure has been investigated by transmission electron microscopy and electron diffraction techniques. it has been found that the whiskers consist of alpha-Fe grains between 2 nm and 30 nm in diameter which do not have sharp boundaries but are separated by a wide boundary region. A microdispersion of alpha-Fe, Fe3O4, Fe3C, alpha-/fe2O3 and carbon is prevalent throughout the whisker volume. Again, no sharp phase boundaries seem to exist which could imply a transitional region between second phase particles characterized by a concentration gradient and mixed covalent and metal bonding. It is concluded that a new strengthening mechanism for alloys is responsible for the mechanical properties of CVD produced steel whiskers. This mechanism requires a grain size below 30 nm, non-planar grain boundaries and a microdispersion of particles of iron oxides, iron carbides and carbon. Also, the covalent/metallic bonding mix within the transition region between the minute second phase particles and the alpha-Fe matrix is considered an essential component of the strengthening mechanism.

Descriptors :   *Whisker composites, *Iron alloys, *Strength(Mechanics), *Tensile strength, Single crystals, Polycrystalline, Filaments, Iron oxides, Carbides, Carbon, Microstructure, Microhardness, Corrosion resistance, Thermodynamics, X ray diffraction, Electron diffraction, Grain boundaries, Spectrum analysis, Bonding, Mechanical properties, Structural properties, Analytical chemistry

Subject Categories : Physical Chemistry
      Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE