Deformation induced structural evolution in bulk metallic glasses |
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Authors: | Gang Wang Norbert Mattern Jozef Bednar?í Lei Xia QiJie Zhai YuanDa Dong Jürgen Eckert |
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Institution: | (1) Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA;(2) Lujan Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545, USA;(3) Department of Physics, University of Idaho, Moscow, ID, 83843, Russia;(4) Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, USA |
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Abstract: | The structural behavior of binary Cu50Zr50 and ternary Cu50Zr45Ti5 bulk metallic glasses (BMGs) under applied stress was investigated by means of in-situ high energy X-ray synchrotron diffraction. The components of the strain tensors were determined from the shifts of the maxima
of the atomic pair correlation functions (PDF) in real space. The anisotropic atomic reorientation in the first-nearest-neighbor
shell versus stress suggests structural rearrangements in short-range order. Within the plastic deformation range the overall
strain of the metallic glass is equal to the yield strain. After unloading, the atomic structure returns to the stress-free
state, and the short-range order is identical to that of the undeformed state. Plastic deformation, however, leads to localized
shear bands whose contribution to the volume averaged diffraction pattern is too weak to be detected. A concordant region
evidenced by the anisotropic component is activated to counterbalance the stress change due to the atomic bond reorientation
in the first-nearest-neighbor shell. The size of the concordant region is an important factor dominating the yield strength
and the plastic strain ability of the BMGs. |
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Keywords: | bulk metallic glasses high energy X-ray diffraction deformation structural evolution |
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