Assessment of the fatigue transformation zone in bulk metallic glasses using positron annihilation spectroscopy

2009 ◽  
Vol 105 (9) ◽  
pp. 093501 ◽  
Author(s):  
M. Liu ◽  
R. S. Vallery ◽  
D. W. Gidley ◽  
M. E. Launey ◽  
J. J. Kruzic
Keyword(s):  
Positron Annihilation ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Positron Annihilation Spectroscopy ◽  
Transformation Zone

scholarly journals Short Range Chemical Ordering in Bulk Metallic Glasses

2000 ◽  
Vol 644 ◽  
Author(s):  
P. A. Sterne ◽  
P. Asoka-Kumar ◽  
J. H. Hartley ◽  
R. H. Howell ◽  
T.G. Nieh ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Critical Density ◽  
Positron Annihilation Spectroscopy ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Chemical Ordering ◽  
Open Volume

AbstractWe provide direct experimental evidence for a non-random distribution of atomic constituents in Zr-based multi-component bulk metallic glasses using positron annihilation spectroscopy. The Ti content around the open-volume regions is significantly enhanced at the expense of Cu and Ni, indicating that Cu and Ni occupy most of the volume bounded by their neighboring atoms while Ti and Zr are less closely packed and more likely to be associated with open-volume regions. Temperature-dependent measurements indicate the presence of at least two different characteristic sizes for the open volume regions. Measurements on hydrogen- charged samples show that the larger open-volume regions can be filled by hydrogen up to a critical density. Beyond this critical density, local atomic-scale open-volume damage is created in the sample to accommodate additional hydrogen. The onset of this local damage in positron annihilation data coincides with the onset of volume expansion in X-ray diffraction data.

scholarly journals Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

2011 ◽  
Vol 59 (5) ◽  
pp. 2057-2068 ◽  
Author(s):  
F. Jiang ◽  
M.Q. Jiang ◽  
H.F. Wang ◽  
Y.L. Zhao ◽  
L. He ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Transformation Zone ◽  
Brittle Transition ◽  
Shear Transformation ◽  
Shear Transformation Zone

Localized heating and fracture criterion for bulk metallic glasses

2006 ◽  
Vol 21 (4) ◽  
pp. 915-922 ◽  
Author(s):  
B. Yang ◽  
C.T. Liu ◽  
T.G. Nieh ◽  
M.L. Morrison ◽  
P.K. Liaw ◽  
...  
Keyword(s):  
Shear Band ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Zone Model ◽  
Transformation Zone ◽  
Localized Heating ◽  
Instantaneous Temperature ◽  
Shear Transformation ◽  
New Criterion

In this study, we demonstrated that the failure of bulk metallic glasses (BMGs) results from a sudden temperature rise within a shear band. Using a shear transformation zone model, we successfully calculated the temperature within a shear band and found it consistent with the observation from an in situ infrared thermographic system. The instantaneous temperature within a shear band at fracture agrees remarkably well with the glass transition temperature (Tg providing a new criterion to determine the strength of BMGs from their Tg. This agreement also discloses the fact that catastrophic failure of BMG is caused by the sudden drop in viscosity inside the shear band when the instantaneous temperature within a shear band approaches Tg.

scholarly journals Relaxation of Free Volume in Zr50Cu40Al10 Bulk Metallic Glasses Studied by Positron Annihilation Measurements

2008 ◽  
Vol 49 (9) ◽  
pp. 1975-1978 ◽  
Author(s):  
Akito Ishii ◽  
Fuminobu Hori ◽  
Akihiro Iwase ◽  
Yuka Fukumoto ◽  
Yoshihiko Yokoyama ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses

High-strength Cu–Ti-rich bulk metallic glasses and nano-composites

2003 ◽  
Vol 94 (5) ◽  
pp. 615-620 ◽  
Author(s):  
Mariana Calin ◽  
Jürgen Eckert ◽  
Ludwig Schultz
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
High Strength ◽  
Nano Composites
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