Characterization of fatigue-induced free volume changes in a bulk metallic glass using positron annihilation spectroscopy

2007 ◽  
Vol 91 (26) ◽  
pp. 261908 ◽  
Author(s):  
R. S. Vallery ◽  
M. Liu ◽  
D. W. Gidley ◽  
M. E. Launey ◽  
J. J. Kruzic
Keyword(s):  
Metallic Glass ◽  
Positron Annihilation ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Positron Annihilation Spectroscopy ◽  
Volume Changes

Characterization of Free Volume in a Bulk Metallic Glass Using Positron Annihilation Spectroscopy

2002 ◽  
Vol 17 (5) ◽  
pp. 1153-1161 ◽  
Author(s):  
K. M. Flores ◽  
D. Suh ◽  
R. H. Dauskardt ◽  
P. Asoka-Kumar ◽  
P. A. Sterne ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Positron Annihilation ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Positron Annihilation Spectroscopy ◽  
Relaxation Processes ◽  
Nickel Copper ◽  
Atomic Relaxation ◽  
Volume Decrease

The free volume of metallic glasses has a significant effect on atomic relaxation processes, although a detailed understanding of the nature and distribution of free volume sites is currently lacking. Positron annihilation spectroscopy was employed to study free volume in a Zr–Ti–Ni–Cu–Be bulk metallic glass following plastic straining and cathodic charging with atomic hydrogen. Multiple techniques were used to show that strained samples had more open volume, while moderate hydrogen charging resulted in a free volume decrease. It was also shown that the free volume is associated with zirconium and titanium at the expense of nickel, copper, and beryllium. Plastic straining led to a slight chemical reordering.

scholarly journals Free-volume Characterization of Polysilanes Using Positron Annihilation Spectroscopy.

1999 ◽  
Vol 12 (5) ◽  
pp. 739-742
Author(s):  
Mutsumi Tashiro ◽  
Shu Seki ◽  
Pradeep K. Pujari ◽  
Yoshihide Honda ◽  
Seiichi Tagawa
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Positron Annihilation Spectroscopy

Free Volume Relaxation Process in Zr50Cu40Al10 Bulk Metallic Glass Studied by Positron Annihilation Techniques

2007 ◽  
Vol 1048 ◽  
Author(s):  
Akito Ishii ◽  
Fuminobu Hori ◽  
Akihiro Iwase ◽  
Yoshihiko Yokoyama ◽  
Toyohiko J Konno
Keyword(s):  
Metallic Glass ◽  
Positron Annihilation ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Structural Relaxation ◽  
Annealing Temperature ◽  
Volume Relaxation ◽  
Appreciable Change ◽  
Positron Annihilation Lifetime ◽  
Chemical Ordering

AbstractStructural relaxation around free volume in Zr50Cu40Al10 bulk metallic glass (BMG) during isothermal annealing at 473, 573 and 673 K which are below glass transition temperature Tg =675 K have been investigated by positron annihilation lifetime (PAL) and coincidence Doppler broadening (CDB) measurements. The trends of change in positron lifetime, which correspond to the size of free volume at each annealing temperature, have a good correlation with their density change. These annealing processes obey a stretched exponential relaxation function (KWW: Kohlrausch-Williams-Watts law). Fitting parameters of KWW function, with relaxation time t0 and β, in each temperature were determined. These relaxation parameters depend on the annealing temperature, suggesting the distribution of activation energy for structural relaxation. Moreover, the profile of electron momentum distribution around free volume derived by CDB spectrum during annealing showed no appreciable change at each temperature. These facts suggest that long range chemical ordering, particularly around the free volume, dose not take place essentially.

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