Distinctive Slow Beta Relaxation And Structural Heterogeneity In (Lace)-Based Metallic Glass

The (LaCe)(32.5)Co20Al15 bulk metallic glass was found to display a pronounced slow beta-relaxation at low temperature, which was well separated by alpha-relaxation based on the mechanical spectroscopy. The activation energy for alpha-relaxation E-alpha is 335 kJ/mol, and this process revealed in the master curve can be well fitted by a Kohlrausch-Williams-Watts (KWW) function with gamma(KWW) value of 0.463. The activation energy for the slow beta-relaxation E-beta is determined to be 76 kJ/mol, which obeys an empirical rule that E-beta equals 22RT(g). The dynamic mechanical behavior of this metallic glass can be well explained by quasipoint defects (QPDs) theory. The correlation factor chi is deduced to be 0.44 from the experimental results, which suggests remarkable heterogeneity in this (LaCe)-based metallic glass. This closely relates to the origin of the prominent slow beta-relaxation. (C) 2018 Elsevier B.V. All rights reserved.