Analysis of β relaxation using internal friction measurement and mechanical testing for a LaCe-based bulk metallic glass

The β relaxation in bulk metallic glasses (BMGs) is reversible and dynamic and is directly related to local atomic cooperative motions. In this study, the effects of thermal cycle and crystallization friction on the reversibility of β relaxation of a LaCe-based BMG are studied by measuring internal friction and by using thermal cycle to certain characteristic temperatures single or repeatedly. Experimental results show that unstable structural units are released after heating to the end temperature of the β relaxation, and partial crystallization does not impede the reversibility but postpones the appearance of the β relaxation. By investigating the atomic mobility and the β relaxation, compression testing at the temperature range that corresponds to the activation of the β relaxation shows a large plastic deformation behavior. •Effects of thermal cycle and crystallization friction on reversibility of the β relaxation of a LaCe-based BMG are studied.•Unstable structural units exist in the as cast BMG and will be released after heating to the end of the β relaxation.•Partial crystallization does not impede the reversibility but postpones the appearance of the β relaxation.