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Title: FeCoSiBNbCu bulk metallic glass with large compressive deformability studied by time-resolved synchrotron X-ray diffraction

By adding 0.5 at. % Cu to the strong but brittle [(Fe{sub 0.5}Co{sub 0.5}){sub 0.75}Si{sub 0.05}B{sub 0.20}]{sub 96}Nb{sub 4} bulk metallic glass, fully amorphous rods with diameters up to 2 mm were obtained. The monolithic samples with 1 mm diameter revealed a fracture strain of 3.80% and a maximum stress of 4143 MPa upon compression, together with a slight work-hardening behavior. SEM micrographs of fractured samples did neither reveal any shear bands on the lateral surface nor the typical vein patterns which characterize ductile fracture. However, some layers appear to have flowed and this phenomenon took place before the brittle final fracture. An estimate of the temperature rise ΔT in the shear plane gives 1039 K, which is large enough to melt a layer of 120 nm. The overall performance and the macroscopic plastic strain depend on the interaction between cleavage-like and viscous flow-like features. Mechanical tests performed in-situ under synchrotron radiation allowed the calculation of the strain tensor components, using the reciprocal-space data and analyzing the shift of the first (the main) and the second broad peak positions in the X-ray diffraction patterns. The results revealed that each atomic shell may have a different stiffness, which may explain the macroscopic compressive plastic deformation. Also, theremore » were no signs of (nano) crystallization induced by the applied stress, but the samples preserve a monolithic amorphous structure until catastrophic failure occurs.« less
Authors:
;  [1] ;  [2] ; ;  [1] ;  [3]
  1. IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, D-01069 Dresden (Germany)
  2. Deutsches Elektronen-Synchrotron (DESY), FS-PE Group, Notkestr. 85, D-22607 Hamburg (Germany)
  3. (Germany)
Publication Date:
OSTI Identifier:
22278095
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AMORPHOUS STATE; BORON ADDITIONS; COBALT ALLOYS; COMPRESSION; CRYSTALLIZATION; FLEXIBILITY; FRACTURES; IRON ALLOYS; MECHANICAL TESTS; METALLIC GLASSES; NIOBIUM ADDITIONS; PLASTICITY; SCANNING ELECTRON MICROSCOPY; SILICON ADDITIONS; STRAIN HARDENING; STRESSES; SYNCHROTRON RADIATION; TIME RESOLUTION; VISCOUS FLOW; X-RAY DIFFRACTION