Indentation creep behavior of a Zr-based bulk metallic glass

Viscosity of Ba–B–Si–Al–O glass measured by indentation creep test at operating temperature of IT-SOFC

“…(14), the activation energy for deformation or viscous flow is determined from the slope of the best fitting line relating to steadystate impression rate versus the reciprocal of temperature, as shown in (standard deviation=1.5 kJ/mol) does not change significantly with the applied stress. By comparing with other glass systems reported in the literature [3], the activation energy for deformation of Ba-B-Si-Al-O glass is lower than that of magnesia-silica (450 kJ/mol) and alkali-silica glass (550 kJ/mol), but is higher than that of lead glass (410 kJ/mol).…”

“…The value of viscosity, which depends on temperature, material and external stress, can be described by the following equation [3]:…”

“…It has been shown that the viscosity and the activation energy of deformation determined by compression or indentation are in good agreement [3]. In addition, several authors [7][8][9][10] have shown that in order to compare the results of impression creep with traditional tensile creep tests, the applied compressive stress and the steadystate impression velocity should be converted to the equivalent tensile stress and strain rate (tensile creep rate) by using the following formulas:…”

“…(14) shows that the activation energy for deformation or viscous flow is determined from the slope of the best fitting line relating to steady-state impression rate and reciprocal of temperature. On the other hand, in order to confirm the stress exponent of a specific material system, the following equation is introduced [3]:…”

Effect of crystallization on the deformation behavior of a Zr-based bulk metallic glass

“…The aim of the present study is to investigate the deformation behavior of a Zr 44 Ti 11 Cu 10 Ni 10 Be 25 BMG during crystallization. In a previous work [6], the glass transition and the crystallization temperatures of this alloy were determined by differential scanning calorimetry (DSC) at 5 K min -1 heating rate as 625 and 725 K, respectively. Indentation creep experiments revealed that in the supercooled liquid state in the temperature range 663 -683 K and at low strain rates (between 5 • 10 -5 and 5 • 10 -4 s -1 ) the deformation can be regarded as Newtonian flow and the viscosity was found to be independent of the strain rate [6].…”