| Title |
A Study on Deformation Modes and Deformation Induced Structural Disordering of a Zr-Based Bulk Amorphous Alloy in Homogeneous Flow Regime |
| Authors |
이광석(Kwang Seok Lee); 박지언(Ji Eon Park); 하태권(Tae Kwon Ha); 장영원(Young Won Chang) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Bulk amorphous alloy; Deformation behavior; Homogeneous flow; Newtonian viscous flow; Non-Newtonian flow; Deformation induced structural disordering |
| 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) |