Initial Oxidation Behavior of Zr55Cu30Al10Ni5 Bulk Metallic Glass in Short-Term Stage

2011 ◽  
Vol 675-677 ◽  
pp. 209-212 ◽  
Author(s):  
Dong Ya Huang ◽  
Bin Wang ◽  
Vincent Ji ◽  
Tao Zhang
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Oxidation Kinetics ◽  
Liquid State ◽  
Glassy State ◽  
Supercooled Liquid ◽  
Short Term ◽  
Initial Oxidation ◽  
Oxygen Ions ◽  
Kinetics Of

The isothermal initial oxidation kinetics of Zr55Cu30Al10Ni5 bulk metallic glass in glassy state (lower than Tg = 685K) and in surpercooled liquid state (Tg = 685 K < T < Tx=774 K) is investigated under dry air by thermogravimetric method in short-term stage (for 1.5 hours). A protective parabolic law is followed in glassy state, except at 573 K where a linear law is followed. The self-limiting oxidation kinetics evolves from a short linear stage to a steady mild growth stage in supercooled liquid state at 723 K, which is induced mainly by crystallization and by the fast growth of dense scale. The growth of the scale is dominated by the formation of tetragonal-ZrO2 (t- ZrO2) in the range of 623 K - 673 K in glassy state for 1.5 hours. The activation energy of oxidation is mainly piloted by the diffusion of oxygen ions.

Air Oxidation Kinetics Study of Zr58Nb3Cu16Ni13Al10 Bulk Metallic Glass

2009 ◽  
Vol 283-286 ◽  
pp. 209-213 ◽  
Author(s):  
Dong Ya Huang ◽  
Xiang Jin Zhao ◽  
Tao Zhang ◽  
Vincent Ji
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Oxidation Kinetics ◽  
Glassy State ◽  
Supercooled Liquid ◽  
Isothermal Oxidation ◽  
Growth Speed ◽  
Air Oxidation ◽  
Two Stages ◽  
Kinetics Of

The isothermal oxidation behavior of Zr58Nb3Cu16Ni13Al10 bulk metallic glass (BMG) under dry air in the glassy state and the supercooled liquid state (SLS) was studied by the thermogravimetric method. The oxidation rate and thickness growth speed in the SLS were both hugely higher than in the glassy state. The oxidation kinetics of BMG in both states for 1.5 hours was different, the parabolic law was followed in the glassy state at 300°C and 350°C, contrarily the linear law was followed in SLS at 400 °C. After the oxidation for 126 hours in SLS, the oxidation kinetics possessed two stages, the linear stage and the parabolic stage. The diffusion of the Cu2+ ion and CuZr intermetallic alloys were detected by GIXRD.

KINETICS AND THERMAL STABILITY OF Nd55Al20Fe25 BULK METALLIC GLASS

2006 ◽  
Vol 20 (05) ◽  
pp. 225-232 ◽  
Author(s):  
L. XIA ◽  
Y. D. DONG
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Stability Limit ◽  
Supercooled Liquid ◽  
Kauzmann Temperature ◽  
The Stability ◽  
Kinetics Of ◽  
Thermal Stability Of

In this work, we studied the thermal stability and kinetics of Nd 55 Al 20 Fe 25 bulk metallic glass (BMG) with distinct glass transition and multistage crystallizations. The kinetics of glass transition and crystallizations were investigated using the Kissinger method and the ideal glass transition temperature of the alloy was obtained via Lasoka's equation. The thermal stability of the BMG was investigated by means of continuous transformation diagrams obtained from the extension of Kissinger analysis. It is suggested that the stability limit of the supercooled liquid, i.e. Kauzmann temperature, could also be regarded as the long-term stability criteria of the BMG.

Structure of Zr52Ti5Cu18Ni15Al10 Bulk Metallic Glass at Elevated Temperatures

2004 ◽  
Vol 443-444 ◽  
pp. 227-232 ◽  
Author(s):  
N. Mattern ◽  
U. Kühn ◽  
J. Sakowski ◽  
J. Neuefeind ◽  
Jürgen Eckert
Keyword(s):  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Liquid State ◽  
Elevated Temperatures ◽  
Supercooled Liquid ◽  
High Energy ◽  
Energy Beam ◽  
Set Up ◽  
Equilibrium Phases

The glass transition and the phase formation during crystallization of the Zr52Ti5Cu18Ni15Al10 bulk metallic glass were followed in situ by high-temperature X-ray diffraction using synchrotron radiation at the high energy beam-line BW5 ( λ = 0.01040 nm) at the storage ring DORIS (HASYLAB, Hamburg). The experimental set-up enables to record intensities in transmission up to scattering vectors q of 200 nm -1 with a measuring time of 20 s per diagram. The crystallization starts with the formation of an extremely fine nanostructure followed by the transformation into tetragonal NiZr2-type crystals plus an unknown phase. Both phases are metastable and transform at about 1123 K into the stable equilibrium phases. The temperature dependence of the structure factor S(q) of the glass can be well described within the framework of the Debye theory. At the glass transition the first derivative dS(q)/dT changes. A Debye temperature Θ = 412 K was estimated for the glassy, and Θ = 162 K for the liquid state of the Zr52Ti5Cu18Ni15Al10 alloy. The short-range order of the glass, of the supercooled liquid state, and of the equilibrium melt at T = 1193 K is found to be quite similar.

Oxidation Behavior of the Y56Al24Co20 Bulk Amorphous Alloy Containing Crystalline Composites at 325-450°C

2007 ◽  
Vol 539-543 ◽  
pp. 2117-2122 ◽  
Author(s):  
H.H. Hsieh ◽  
W. Kai ◽  
C.Y. Lin ◽  
Tsung Shune Chin
Keyword(s):  
Amorphous Alloy ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Rate Constants ◽  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Bulk Amorphous Alloy ◽  
Temperature Dependent ◽  
Dry Air ◽  
Kinetics Of

The oxidation behavior of Y56Al24Co20 bulk metallic glass containing ~4.2% Y-rich particles was studied over the temperature range of 325-450oC in dry air. The results showed that the oxidation kinetics of the alloy followed the parabolic rate law at T≤375oC, with rate constants generally increased with temperature. Conversely, para-linear kinetics were observed at higher temperatures (T≥400oC). The scales formed on the Y-base amorphous composite were temperature dependent, consisting of exclusively yttrium oxides (Y2O3) at T≤375oC and of mostly Y2O3 and alumina (Al2O3) at temperatures. No evidence of any cobalt-containing oxide was found in the scale.

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