Correlation between structures and properties in (Zr 65 Cu 15 Ni 10 Al 10 ) 90 Nb 10 alloys
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Ying Min Wang School of Materials Science and Engineering, Dalian University of Technology, Dalian, 116024, People’s Republic of China
Chan Hung Sheka) Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, People’s Republic of China (Received 12 July 2011; accepted 25 January 2013)
A quasicrystal (QC)- based alloy composite was made by copper mold casting under a low-vacuum level condition at the bulk metallic glass (BMG)- forming composition (Zr65Cu15Al10Ni10)90Nb10. The QC alloy consisted of a majority of icosahedral quasicrystal phase and a small amount Zr-rich glassy phase. Under uniaxial compression at room temperature, the BMG alloy exhibits a certain plastic strain; the QC alloy is much stronger but brittle. The icosahedral glass model was used to describe the I-phase structure. The structure–property relations of the BMG and QC alloys are discussed assuming the common preferential icosahedral atomic structure in both cases and the existence of local glue structure in the BMG structure.
I. INTRODUCTION
Bulk metallic glasses (BMGs) have attracted more attention due to their unique combination of properties such as high strength-to-weight ratio, high strength approaching the theoretical value, excellent wear- and corrosion resistance, good soft magnetic properties.1,2 Most of the BMG alloys are associated with multicomponent compositions. Diffraction probes like x-ray or neutron diffraction can provide only the average information on first-coordinate number and first-neighbor distance for these complex alloys, and their atomic scale structures are so far not known. It is generally agreed that metallic glasses show similar structure to its undercooled liquid form, as metallic glasses are mostly made by rapid cooling of molten liquid metals.3,4 The early studies on structures of metallic glasses followed the investigations on local structure of simple liquids.5 Some of the best known studies are the Frank’s hypothesis of 13 atoms local icosahedral clusters6 and the dense random packing of hard sphere model proposed by Bernal.7 Recent results of structural studies supported that Frank’s hypothesis still works in multicomponent BMG-forming liquids.8,9 To explain the strong preference of icosahedral short-range order (ISRO) in BMGs, effective atomic packing including preferential ISRO is required based on the statistical information given by diffraction. Following the principle of efficient spatial filling, Miracle proposed an efficient clustera)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2013.22 1218
J. Mater. Res., Vol. 28, No. 9, May 14, 2013
http://journals.cambridge.org
Downloaded: 19 Mar 2015
packing model, in which close packing I-clusters or cubiclike solute-centered clusters are retained in BMGs as local representative structural elements.10,11 The idea of glue or bridge atoms linking the icosahedral unit clusters was also proposed by Dong et al.12 Quasicrystal (QC) is another kind of alloys, which do not have any long-range p
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