Accession Number : ADA288391

Title :   Synthesis and Structural Properties of New Metallic Phases Exhibiting Non-Crystallographic Symmertries.

Corporate Author : VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Poon, S. J. ; Shiflet, G. J.

PDF Url : ADA288391

Report Date : 15 AUG 1994

Pagination or Media Count : 7

Abstract : In carrying out research on aluminum-glasses (Al-glasses), several unusual results are found: sub millimeter dutile glassy ribbons are obtained. Significant enhancement in the tensile strength is measured in Al-glass ribbons with Al nanocrystallites embedded in them. Deformation induced crystallization within the shear bands is observed for the first time. Strong Al-transition metal interaction is inferred from x-ray and neutron diffraction measurements. These results have added to our understanding of formation and microstructure-mechanical effect relationships of metal-glasses, and also to the technological values of these materials. We have begun to apply our findings to the synthesis and studies of bulk metallic-glass and nanocrystalline alloys. Thus far, we have succeeded in making subcentimeter glasses based on rare-earths and magnesium-tin, nanocrystalline alloys based on refractory metals via conventional casting, and as well as, centimeter Al-glass button via consolidation of amorphous powders obtained by ball-milling. In collaboration with Professor T. Egami at U. Penn., a method for obtaining two-dimensional atomic pair distribution is developed to unravel the structure of decagonal crystals. The new method will be applied to study layered materials.

Descriptors :   *METALS, *SYNTHESIS, *STRUCTURAL PROPERTIES, *PHASE, *SYMMETRY, BANDS(STRIPS), SHEAR PROPERTIES, MAGNESIUM, MEASUREMENT, TENSILE STRENGTH, TRANSITION METALS, LAYERS, MATERIALS, POWDERS, DEFORMATION, AMORPHOUS MATERIALS, CRYSTALLIZATION, CRYSTALS, GLASS, ALLOYS, CASTING, NEUTRON DIFFRACTION, REFRACTORY METALS, TIN.

Subject Categories : Physical Chemistry
      Inorganic Chemistry
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE