Main (α) relaxation and excess wing in Zr50Cu40Al10 bulk metallic glass investigated by mechanical spectroscopy

The dynamic mechanical relaxation behaviour of Zr50Cu40Al10 bulk metallic glass was investigated by mechanical spectroscopy as a function of temperature. The mechanical spectra show the evidence of an “excess wing” process at the lower temperatures. The α-relaxation spectra of Zr50Cu40Al10 bulk metallic glass was described with a Kohlrausch-Williams-Watts (KWW) function, with the exponent βKWW = 0.5 ± 0.02. The fragility parameter m of the Zr50Cu40Al10 is m = 57 ± 5. The values of m and βKWW are found to agree with the correlation found for other glasses m = 250(± 30) − 320 βKWW [R. Böhmer, K.L. Ngai, C.A. Angell et al. J. Chem. Phys. 99 (1993) 4201-4209]. Aging experiments give strong evidence that the observed “excess wing” is a submerged secondary process and not part of the α process.