Hu, L. N.6; Zhou, C.6; Zhang, C. Z.6; Yue, Yuanzheng1
1 Section of Chemistry, The Faculty of Engineering and Science, Aalborg University, VBN2 Inorganic Amorphous Materials, The Faculty of Engineering and Science, Aalborg University, VBN3 Department of Chemistry and Bioscience, The Faculty of Engineering and Science, Aalborg University, VBN4 The Faculty of Engineering and Science (ENG), Aalborg University, VBN5 Shandong University6 Shandong University
Recently, we observed an unusual non-monotonic glass relaxation phenomenon, i.e., the three-step sub-Tg relaxation in hyperquenched CuZrAl glass ribbons [L. N. Hu and Y. Z. Yue, Appl. Phys. Lett. 98, 081904 (2011)]. In the present work, we reveal the origin of this abnormal behavior by studying the cooling rate dependence of the sub-Tg enthalpy relaxation in two metallic glasses. For the Cu46Zr46Al8 glass ribbons the sub-Tg enthalpy relaxation pattern exhibits a three-step trend with the annealing temperature only when the ribbons are fabricated below a critical cooling rate. For the La55Al25Ni20 glass ribbons the activation energy for the onset of the sub-Tg enthalpy relaxation also varies non-monotonically with the cooling rate of fabrication. These abnormal relaxation phenomena are explained in terms of the competition between the low and the high temperature clusters during the fragile-to-strong transition. By comparisons of chemical heterogeneity between Cu46Zr46Al8 and La55Al25Ni20, we predict that the abnormal relaxation behavior could be a general feature for the HQ metallic glasses.
Journal of Chemical Physics, 2013, Vol 138, Issue 17