Accession Number : ADA621014


Title :   Local Atomic Structure of Ca-Mg-Zn Metallic Glasses (Postprint)


Descriptive Note : Journal article


Corporate Author : AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE


Personal Author(s) : Senkov, O N ; Miracle, D B ; Barney, E R ; Hannon, A C ; Cheng, Y Q ; Ma, E


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a621014.pdf


Report Date : 16 Sep 2010


Pagination or Media Count : 17


Abstract : The amorphous structure of four Ca60MgXZn40-X (X=10, 15, 20, and 25 at. %) ternary metallic glasses (MGs) has been investigated by neutron and x-ray diffraction, using Reverse Monte Carlo modeling to simulate the results. A critical analysis of the resultant models, corroborated by ab initio molecular-dynamics simulations, indicate that the glass structure for this system can be described as a mixture of Mg- and Zn-centered clusters, with Ca dominating in the first coordination shell of these clusters. A coordination number (CN) of 10 [with about 7 Ca and 3(Mg+Zn) atoms] is most common for the Zn-centered clusters. CN=11 and 12 [with about 7-8 Ca and 4 (Mg+Zn) atoms] are most common for Mg-centered clusters. Fivefold bond configurations (pentagonal pyramids) dominate (60%) in the first coordination shell of the clusters, suggesting dense atomic packing. Bond-angle distributions suggest near-equilateral triangles and pentagonal bipyramids to be the most common nearest atom configurations. This is the systematic characterization of the structure of Ca-Mg-Zn MGs, a category of bulk MGs with interesting properties and intriguing applications. It is also the experimental verification of the principle of efficient packing of solute-centered clusters in ternary MGs.


Descriptors :   *ATOMIC STRUCTURE , *METALLIC GLASS , ALLOYS , AMORPHOUS MATERIALS , BONDING , CLUSTERING , MOLECULAR DYNAMICS , MONTE CARLO METHOD , NEUTRON DIFFRACTION , STRUCTURAL ANALYSIS , TERNARY COMPOUNDS , X RAY DIFFRACTION


Subject Categories : Metallurgy and Metallography
      Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE