TY - GEN
T1 - Free volume relaxation process in Zr50Cu40Al 10 bulk metallic glass studied by positron annihilation techniques
AU - Ishii, Akito
AU - Hori, Fuminobu
AU - Iwase, Akihiro
AU - Yokoyama, Yoshihiko
AU - Konno, Toyohiko J.
PY - 2008
Y1 - 2008
N2 - Structural relaxation around free volume in Zr50Cu 40Al10 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 trend of change in positron lifetime, which corresponds to the size of free volume at each annealing temperature, has a good correlation with their density change. These annealing processes obey a stretched exponential relaxation function (KWW: Kohlrausch-Williams-Watts law). The relaxation time t0 and β, used as adjustable parameters in the KWW function, were determined at each temperature. These relaxation parameters depend on the annealing temperature, suggesting the distribution of activation energy for structural relaxation. Moreover, the profile of the electron momentum distribution around free volume derived from CDB spectra 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.
AB - Structural relaxation around free volume in Zr50Cu 40Al10 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 trend of change in positron lifetime, which corresponds to the size of free volume at each annealing temperature, has a good correlation with their density change. These annealing processes obey a stretched exponential relaxation function (KWW: Kohlrausch-Williams-Watts law). The relaxation time t0 and β, used as adjustable parameters in the KWW function, were determined at each temperature. These relaxation parameters depend on the annealing temperature, suggesting the distribution of activation energy for structural relaxation. Moreover, the profile of the electron momentum distribution around free volume derived from CDB spectra 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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M3 - Conference contribution
AN - SCOPUS:70350331919
SN - 9781605608433
T3 - Materials Research Society Symposium Proceedings
SP - 101
EP - 106
BT - Bulk Metallic Glasses - 2007
T2 - 2007 MRS Fall Meeting
Y2 - 26 November 2007 through 30 November 2007
ER -