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Vol.43, No.4, 276 ~ 286, 2005
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| Title |
| A Study on Deformation Modes and Deformation Induced Structural Disordering of a Zr-Based Bulk Amorphous Alloy in Homogeneous Flow Regime |
| 이광석 Kwang Seok Lee , 박지언 Ji Eon Park , 하태권 Tae Kwon Ha , 장영원 Young Won Chang |
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| Abstract |
| Deformation behavior of a Zr_(41.2)Ti_(13.8)C_(u12),Ni_(10)Be_(22.5) bulk metallic glass was investigated. Three different types of true stress-strain curves were identified under compressive loading within undercooled liquid region depending on the strain rates and test temperatures. The two theoretical relations, based on a Newtonian viscous flow equation and a transition state theory, have been applied to analyze the transition behavior of deformation modes in homogeneous flow regime in terms of steady-state flow stress. In addition, the change of glass transition peak height by Differential Scanning Calorimetry (DSC) and qualitative RDF by Extended X-ray Absorption Fine Structure (EXAFS) have been used to account for structural states of Zr_(41.2)Ti_(13.8)C_(u12),Ni_(10)Be_(22.5) bulk amorphous alloys after annealing and disrupted compression test at =10^(-3)/s. At 370℃, only a small structural relaxation was observed to proceed in a period of 680 s by annealing. A deformation induced structural disordering (DISD) was, on the other hand, observed at the initial state of a non-Newtonian flow (e=0.03 and 0.076) around the stress overshoot. (Received November 26, 2004) |
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| Key Words |
| Bulk amorphous alloy, Deformation behavior, Homogeneous flow, Newtonian viscous flow, Non-Newtonian flow, Deformation induced structural disordering |
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